Why cant my code behind page acces variables in View Model

Why doesnt my View recognize email and password strings from View Model.
It says that email and password dont exist in current context. Can someone tell me why doesnt this code work and explain solution?
this is code in View:

using System;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using Papucometar.ViewModel;
using Xamarin.Essentials;
namespace Papucometar.View
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class LoginUI : ContentPage
    {
        public LoginUI()
        {
            var vm = new LoginViewModel();
            this.BindingContext = vm;
            vm.DisplayInvalidLoginPrompt += () => DisplayAlert("Error", "Invalid Login, try again", "OK");
            InitializeComponent();

            email.Completed += (object sender, EventArgs e) =>
            {
                Password.Focus();
            };

            Password.Completed += (object sender, EventArgs e) =>
            {
                vm.SubmitCommand.Execute(null);
            };
        }
    }
}

And this is ViewModel code:

using System.ComponentModel;
using System.Text;
using System.Windows.Input;
using Xamarin.Essentials;
using Xamarin.Forms;

namespace Papucometar.ViewModel
{
    public class LoginViewModel : INotifyPropertyChanged
    {
        public Action DisplayInvalidLoginPrompt;
        public event PropertyChangedEventHandler PropertyChanged = delegate { };
        private string Email;
        public string email
        {
            get { return Email; }
            set
            {
                Email = value;
                PropertyChanged(this, new PropertyChangedEventArgs("Email"));
            }
        }
        private string password;
        public string Password
        {
            get { return password; }
            set
            {
                password = value;
                PropertyChanged(this, new PropertyChangedEventArgs("Password"));
            }
        }
        public ICommand SubmitCommand { protected set; get; }
        public LoginViewModel()
        {
            SubmitCommand = new Command(OnSubmit);
        }
        public void OnSubmit()
        {
            if (email != "macoratti@yahoo.com" || password != "secret")
            {
                DisplayInvalidLoginPrompt();
            }
        }
    }
}

IntelliSense says that these variables dont exist. I cant figure out why they cant see each other.
This is xaml code

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Papucometar.View.LoginUI"
             xmlns:local="clr-namespace:Papucometar.ViewModel"
             x:DataType="local:LoginViewModel"
             BackgroundColor="#112B47">
    <ContentPage.Content>  
    <StackLayout Orientation="Vertical" Padding="30" Spacing="40">  
        <BoxView HeightRequest="10"/>  
        <Image HorizontalOptions="Center" WidthRequest="300" Source="maco.jpg"/>  
        <Frame BackgroundColor="#BF043055" HasShadow="False">  
            <StackLayout Orientation="Vertical" Spacing="10">  
                <Entry x:Name="Email" Text="{Binding Email}" Placeholder="Email"   
                       PlaceholderColor="White" HeightRequest="40"   
                       Keyboard="Email"  
                       TextColor="White"/>  
                <Entry x:Name="Password" Text="{Binding Password}" Placeholder="Senha"   
                       PlaceholderColor="White" HeightRequest="40"   
                       IsPassword="True"  
                       TextColor="White"/>  
            </StackLayout>  
        </Frame>  
        <Button Command="{Binding SubmitCommand}" Text="Login" TextColor="White"  
                FontAttributes="Bold" FontSize="Large" HorizontalOptions="FillAndExpand"  
                BackgroundColor="#088da5" />  
    </StackLayout>  
</ContentPage.Content>  
</ContentPage>

Update

I notice that you use the following code in code behind to add a Completed event to an Entry，

email.Completed += (object sender, EventArgs e) =>
{
    Password.Focus();
 };

But in your xaml, you set x:Name="Email"

 <Entry x:Name="Email" Text="{Binding Email}" 

So you know it's case sensitive. The email in code behind refers to the Entry (with x:Name="email") set in xaml instead of email property in ViewModel. That's why you got "email does not exist in the current context".

By the way, if you want to access the ViewModel variables from code behind, you could use:

var password = vm.Password;

============Origin answer======

You have done most of the work. But capitalization conventions and some details should be paid more attention to, as ToolmakerSteve mentioned.

In the ViewModel, you define the Email property in this way:

    private string Email;
    public string email
    {
        get { return Email; }
        set
        {
            Email = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Email"));
        }
    }

That means Email string is a private variable and only in the same class can access it.

If an outside class want to access it, it can be done with properties. That's email property in your code. So other class can only access the Email string through email property, to be explicit, through
getter in email property.

Another is capitalization conventions. Usually we set the private field to lower case while the property name to upper case.

To conclude, you may change email property to this:

    private string email;
    public string Email
    {
        get { return email; }
        set
        {
            email = value;
            PropertyChanged(this, new PropertyChangedEventArgs(nameof(Email)));
        }
    }

Hope it works.