Oracle Apex doesn't show existing schema - oracle

Question

I have a problem with connecting data from my local oracle user schema (USERS table space) and apex workplace.
Could you adivise how I can connect apex workplace with my existing schema?
It looks like APEX uses its own table space and ignores my schemas.
Here are my screenshots:
SQL Developer screen Creating a new workspace screen
Forgot one significat thing to mention: schema Pavel in Apex and schema Pavel in SQL Developer are different. Tables, which are created in the Apex in schema Pavel, are not seen in SQL Developer.
No apex user screen
apex create workplace and new schema dialog (different table space), the schema is not visible in sql developer

Answer 1

See whether following helps:
Connect to the database as SYS and check your Apex users:
SELECT * FROM ALL_USERS WHERE USERNAME LIKE 'APEX%',
Suppose there's APEX_180200 listed (and you use it). Then:
ALTER SESSION SET CURRENT_SCHEMA = APEX_180200;
BEGIN
APEX_INSTANCE_ADMIN.UNRESTRICT_SCHEMA(P_SCHEMA => 'ADAM');
COMMIT;
END;
/
Now check whether you can assign the ADAM schema to your workspace.

Answer 2

you will need to add your existing schema to your APEX workspace:
check out oracle docs for this:https://docs.oracle.com/database/121/AEAPI/apex_instance.htm#AEAPI253
BEGIN
APEX_INSTANCE_ADMIN.ADD_SCHEMA('MY_WORKSPACE','FRANK');
END;

Answer 3

The problem was in misunderstanding oracle database architecture.
The APEX data was stored in the pluggable database, while the default connection in SQL Plus was to the root container cdb$root.
alter session set container = XEPDB1;