Stay alive!!!

Okay...
1) The numbers need to be clarified – that's correct!
2) Regarding the "active forum user" – I suggest asking the creator to make this automatic. That is, until 2 months have passed, it's not allowed (i.e., there's no "request to create a clan" button). Two criteria will be the number of posts. So, if a user logs in once and then again after 2 months, and they don't have any posts, the "button" will still be missing.

What about the fact that some ACTIVE clans will have a few people who don't meet the requirements? What should be done with them – exclude them?

No. Active users are the 4 minimum people needed to join a clan. That is, only they should have the required number of posts and Battle.net ID (B.net ID). But you can outline different requirements for them – for "COMBAT" or "ANALYTICAL" clans. That is, the number of posts and the type of activity before clan registration will differ! For example: for 3 (excluding the leader – he has separate requirements) members of a future "COMBAT" clan, it's not necessarily required to have "N" posts, but then they must participate in a tournament before or during the creation of the clan (the Warlord's Cup runs year-round!) + a report on participation in tournaments (it doesn't have to be written by the fighters themselves; the leader of the future clan can write it). For 3 members of an "ANALYTICAL" clan, there will be different requirements – that is, they must have "N*2" posts and a report on the work done! (it doesn't have to be written by the analysts themselves; the leader of the future clan can write it).
And the rest can be accepted even if they are completely new (0 posts, neutral B.net ID)!