Nostalrius Begins - Quality wow vanilla realm (1.12)

I can login and connect fine, but once being able to choose the realm I'd like , it simply wont take me into the realm to start playing.

Which realm were you attempting to get onto? The PvP realm went down, it was still visible under the "Choose Realm" menu but it wouldn't bring you to a character list. Hopefully you just tried to get in during this window. If this happens again check the Nostalrius homepage: https://en.nostalrius.org/ and confirm the server is online.

Realms might be crashing or even locked.