regarding Paramount+

I signed up through my Mytmobile account in line add ons.

I received an email from T-Mobile with my Paramount + credentials. I'd give Tech Support a call and find out how to get them, or have them resend them to you. Once you have that, you're good to go.

Did you sign up through Tmobile or  Paramount?.

https://www.t-mobile.com/offers/paramount-plus-deal

I have my login and password for t-mobile but have not received anything for Paramount+ after I agreed to the promo.

Do you have an log in and password? If so download the app and sign in.