Great!
As i have written here above, the next step is to check out Repeater - Velo API Reference - Wix.com
And query the number of followers, and if the current user is among them
Caching the data for better performance is adding another column to a profile, updating it +1 when a follower is added. As for current user, you can query the list of profiles the current user is following and holding it in local cache, then check that on each repeater render to decide if the button should be disabled or not