hi, no problem.
bases become raidable after X days of being inactive - do not think of it as purge, that is a different feature
purge day is when every single base on the server becomes raidable. you must run the commands sar purge and sab to enable it.
by default each base despawns after 1800 seconds so on purge day you may want to set this time to 0 so they do not despawn until you wipe the map
no, you cannot avoid purge day for specific people unless they have exempt perm
it is advised that you run the purge commands after a restart and before anyone logs on. this can be very stressful on the server and kick players otherwise. it is not recommended to use this feature until the next update can resolve this
either way, TruePVE and Abandoned Bases should always be unloaded on purge day anyway