First of all, you must have a TuneIn/Deezer account, and then you must enter the credentials in the Bang & Olufsen app* to log in to the account on your music system. If you do not have a TuneIn or Deezer account, you can sign up via the TuneIn/Deezer webpages:
TuneIn: https://tunein.com/account/new/signup/
DEEZER: http://www.deezer.com
Note that TuneIn and Deezer may not be available in all markets.
*How to add your Deezer or TuneIn credentials to the Bang & Olufsen app