The regular Game Maker Community basically has everything you need: https://forum.yoyogames.com/index.php
(It's sort of official - it's not run by Yoyo directly but several of the staff members visit regularly and it's commonly accepted as the main place to exchange information)
There's also a game maker discord, I don't have the link to it but it's probably not super hard to find? (Left it years ago after some drama)