Hi,
next step is configuring the relationship table, profile followers - it should include a references to the profile collection. please configure 2 columns each of type reference to the matching collection.
when you query this relationship table you can know for each user, how many followers he has, or the profiles he follows.
you can implement code to decide if a follow button should be displayed on the repeater, in case the current user is not already following the repeater profile, please have a look here - Repeater - Velo API Reference - Wix.com
clicking on the follow button of the repeater should add a record to this table using wix-data insert
https://www.wix.com/code/reference/wix-data.html#insert
you can also create a calculated field for each profile, or update a column on the profile collection with the number of followers (on add/remove follower) so in the repeater you can display the number of followers directly from the profile collection data set
good luck!
Shlomi