You should have gotten a copy of your HOA rules when you purchased a house. If you didn't you should be able to get one from the property management company. There's probably a portal through the property management company that has everything listed and where you can pay dues. What happens typically is first warning which sounds like you just received. After that wkll come fines. If you refuse to pay the fines then lien. Of you still refuse they could foreclose on your house.

If you don't like an HOA don't move to neighborhood with one. They have their good and bad aspects. One thing to remember is the HOA IS your neighbors. Don't like the rules. Go to the meetings. Volunteer for the board. Vote. Be an active participant in your community. It isn't a dictatorship. There are laws regulating HOA's but most people would rather bitch than do