Here's how your friend needs to log in with Voyager:

Instance: Yes, they need to specify europe.pub as their instance. In Voyager, when you add an account, there's a field for the instance URL — they'd enter europe.pub (or https://europe.pub/). That's how the app knows which server to talk to.

Login credentials: They use their username and password, not their email. The username is the one they chose when they registered on europe.pub (the part before the @ in username@europe.pub). So if their full Lemmy name is johndoe@europe.pub, they'd type johndoe as the username and their password.

So the two things your friend likely got stuck on:

1. Forgetting to set the instance to europe.pub
2. Trying to log in with their email instead of their Lemmy username

That should get them in.