Six teams in a group, just three groups, three fields, one for each group. Group match, one group plays 15 games. If each team takes two teams here, there will be a bye in the knockout round. So I suggest that each team take 2 teams, and then take 2 teams (record, net victory, etc. ). In this way, there are 8 teams, which are eliminated by lottery and finally just right (similar to NBA).
There will be a group match in the first three days, so please arrange your own time. The last three days will only be three rounds of elimination, eight teams, and the final day+three or four places.