I'd assume if 3 teams make it out of both groups its.
1st : Alpha 1
2nd: Omega 1
3rd: Alpha 2
4th: Omega 2
5th: Alpha 3
6th: Omega 3

i think if you dont keep a core of 3 your vlr rank essentially resets and you need to play a few games before you get one again

Frieren and Dungeon Meshi are both pretty good