First off, thank you for playing Praxis! There is a limit to how many coterie members you can have and it’s based on your rank. The higher the rank, the bigger your coterie can be.
You can defeat the anarch threat by defeating all four anarch attacks that will happen randomly after the anarch revolt starts. Sometimes it takes a while for all of them to trigger, so be sure to give it a minuet.
Hopefully that helps. Let me know if you have any more questions or issues.