How to add a standby database to the OEM 13C release4

I have a single instance database running on oracle 19.10 and linux redhat enterprise 7

I created a standby database for the single instance and it has been running for two days now.

SQL> select DB_UNIQUE_NAME,DATABASE_ROLE, OPEN_MODE from v$database;

DB_UNIQUE_NAME            DATABASE_ROLE   OPEN_MODE

------------------------------ ---------------- --------------------

drnprd               PHYSICAL STANDBY MOUNTED

I want to add this database to the enterprise manager to be managed as a dataguard db- I have to add it to the EM but I get the following error:

ORA-01033: ORACLE initialization or shutdown in progress The Connect Descriptor was (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = xxx)(PORT = 1521))(CONNECT_DATA = (SID = drnprd)(SERVER = DEDICATED)))