SlickStack does not require Git Updater. It is not even installed by default. However our default (free) WordPress theme called HoverCraft does require it if you want to receive free updates from GitHub:
If you want the LittleBizzy team to setup your SlickStack cloud server for you and migrate all your data, we can do it for a fixed price at the below link. If you're not satisfied, request a 100% refund anytime you want (no questions asked).