Hi Chandan,
Have you run the below grant select querry for the schema in which you created the tables?
GRANT SELECT ON SCHEMA <your_schema_name> TO _SYS_REPO WITH GRANT OPTION;
If grant select authorization is not there for _SYS_REPO user for the schema you are using, activation will fail with 'Insufficient privileges - not authorized' error.
Regards,
Rashmi