Regarding the checks, the initial free plan (just following my bot) comes with weekly checks. That means I'll fetch your followers once a week and compare with last week's, find out who is missing and sending you a DM with the list of all unfollowers. So you'll basically a weekly DM with unfollowers.

Daily, hourly and realtime plans work in the same way but with a higher frequency, but without any kind of digest, just one DM with the list of unfollowers in the time window.