The first query should return three rows:
SELECT username FROM all_users WHERE username LIKE 'APEX_%' OR username LIKE 'FLOWS_%'; SELECT comp_id, comp_name, status FROM dba_registry WHERE comp_id='APEX';
The second one row:
FLOWS_FILES APEX_PUBLIC_USER APEX_040000
If that's not the case, your APEX is not installed properly.
APEX Oracle Application Express VALID