How to display data based on value in another table?

I have a Interactive Report which displays data for multiple divisions, column name D365LE.

I also have a users table which contains the same column name, depending on which division the employee is a part of.

I'm able to display the data which only correlates to the users division using the following:

select * from D365_PURCHASE_INVOICE_STAGING 
where upper(company) = (SELECT u.D365LE FROM USERDETAILS u WHERE upper(u.username) = upper(:app_user))

In the USERDETAILS table there is a column called ROLE which holds whether the user is an admin or not. I want the report to display all data if the user is Admin, and if not it should only show the data which correlates to their division, as above.

I've tried the following, which does compile but displays no data:

select s.* from D365_PURCHASE_INVOICE_STAGING s
INNER JOIN USERDETAILS u
    on s.COMPANY = u.D365LE
where (u.ROLE = 'Admin')
or 
(upper(s.COMPANY) = (SELECT u.D365LE FROM USERDETAILS WHERE upper(u.USERNAME) = upper(:app_user)))
and (u.ROLE <> 'Admin')

Something like this, perhaps?

Sample data:

SQL> with
  2  d365_purchase_invoice_staging  (company) as
  3    (select 'Apple' from dual union all
  4     select 'IBM'   from dual
  5    ),
  6  userdetails (username, d365le, role) as
  7    (select 'LITTLE', 'IBM'  , 'Admin' from dual union all
  8     select 'FOOT'  , 'Apple', 'Clerk' from dual
  9    )

Query:

 10  select *
 11  from d365_purchase_invoice_staging d
 12  join userdetails u on d.company = u.d365le
 13  where u.username = case when u.role <> 'Admin' then u.username
 14                          else '&APP_USER'
 15                     end;
Enter value for app_user: LITTLE          --> admin

COMPA USERNA D365L ROLE
----- ------ ----- -----
IBM   LITTLE IBM   Admin
Apple FOOT   Apple Clerk

SQL> /
Enter value for app_user: FOOT           --> not admin

COMPA USERNA D365L ROLE
----- ------ ----- -----
Apple FOOT   Apple Clerk

SQL>

(this was ran in SQL*Plus so I used substitution variable, '&APP_USER'. You'd use :APP_USER as you normally do in Apex).

You can use:

select *
from   D365_PURCHASE_INVOICE_STAGING d
where  EXISTS(
         SELECT 
         FROM   USERDETAILS u
         WHERE  upper(u.username) = upper(:app_user)
         AND    (  upper(company) = u.D365LE
                OR u.role = 'Admin' )
       )