There's no limit on the total number of fans you can follow.
However, OnlyFans limits how many fans can be followed per day, so the Expired Fans Automation paces itself at roughly 100–200 follows per day to stay within platform limits and keep your account safe.
To make the most of each day's followers, the Auto-Follower never follows other creators, so you won't be charged for your following, and follows your most valuable fans first.
See "Expired Fans Automation" for setup and best practices.