First 2 in each group and 4 best 3rd placed teams (ranking excluding matches with last placed) qualify for the Euro.
I find this system very stupid and a bit unfair. If you have eight 3rd placed teams, it makes much more sense to organize a playoff for the last 4 spots.
Hosts Hungary and Slovakia, as well as Euro 2020 finalists Spain and Croatia are already qualified and will probably play that "nations cup" thingy in parallel with the qualification groups.
Groups 3, 4, 5 and especially 7 look very balanced.