If you face error on login to golden gate inspite of using the right password then have a look at sec_case_sensitive_logon paremeter. chnage its value if you have no impact

GGSCI (rac01) 4> dblogin UserID ggadmin@ICP02TST, Password ggadmin
ERROR: Unable to connect to database using user ggadmin@ICP02TST. Ensure that the necessary privileges are granted to the user.
OCI Error ORA (status = 1017-ORA-01017: invalid username/password; logon denied
).

SQL> sho parameter sec_case_sensitive_logon

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sec_case_sensitive_logon             boolean     FALSE
SQL> alter system set sec_case_sensitive_logon=TRUE scope=both sid='*';

System altered.

SQL>  sho parameter sec_case_sensitive_logon

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sec_case_sensitive_logon             boolean     TRUE


GGSCI (rac01) 5> dblogin UserID ggadmin@ICP02TST, Password ggadmin
Successfully logged into database.