If you previously subscribed to the bundle through SHOWTIME (this version of the bundle is still supported, but it is no longer an option for new subscribers) and you have not yet activated your subscription on Paramount+, go to paramountplus.com/showtime. You'll be prompted to sign in using your SHOWTIME username and password (you'll only need to do this once), and then either create or sign into a Paramount+ account.
IMPORTANT NOTE: Once you activate your subscription on Paramount+, you will log in to paramountplus.com or the Paramount+ app USING YOUR PARAMOUNT+ ACCOUNT CREDENTIALS, not your SHOWTIME email and password.