I need to add my phone number

Alright, I understand what you're saying, but what exactly do you expect from us?

You mentioned that you're unable to access your Gmail account at work because it's not allowed, yet you're permitted to listen to music.

So that shouldn't really be a problem, should it? You don't need a Gmail account to use Deezer.

You can simply log in with your Deezer credentials and that's it, just enjoy!