I want to manually register member information in the back-end via a “profile” database, so members will be given login information instead of registering for a profile themselves. In this “profile” database, I already added in member email and password.
After I created a custom login page (connected to “profile” database), a “PrivateMemberData” database was auto-generated. What is this “PrivateMemberData” database used for?

@russian-dima Thanks for the link. My question is why is this database auto-generated and what is the purpose of using the PrivateMemberData database vs. a profile database?
The PrivateMembersData (PMD) is auto-generated when you implement a Member-Area. It is used for REGISTRATIONS and User-Log-Ins.
Without this you can’t access / can’t log-in.
You could also create your own database, but you would not be able anymore to use all of Wix-Apps and features.