Posts aren't actually a factor when applying to a clan.
If you don't post there's nothing we can do bout it, and they only way to increase your post count (which in itself is pointless) is to find places that do interest you.
Organisations for people with a common interest for example, and off topic for just a casual chat bout a specific topic of interest.
You are not allowed to require a certain number of posts from users to enter your clan.