If I may, I'll share some thoughts and a question.
Is this an original band or a cover band?
As has been stated, if it's an original band they may want you to bring something fresh into the mix, or not. If it's a cover band, find out if they want replication of the original or if they put their own spin on tunes.
I joined a busy cover band almost two years ago and had to learn 50 tunes in two weeks. They stay pretty true to the recordings. It wasn't hard, it just took time. The guitar player had chord charts for pretty much everything but I learned most of it by ear because I don't like reading charts on stage.
I was a bit lazy at first because in my last band I sang a lot. In the new band I didn't have to do any singing (at first) and just played bass. But now I'm singing a bunch, lead and harmony. Like most of us singing bass players, I play better when I don't have to sing but I do enjoy a bit of the limelight once in a while.
Anyway, just go in there with a good attitude. Ask them what is expected and then deliver it.
And break a leg!
Thank you for your indulgence,