Plugin CUP Costumer User Profile on Confluence - migrate user values

I just got the trial of the Custom User Profile plugin on Confluence and I have some some questions. The first thing I see is a yellow box saying “Migrate user values into cup fields”. Before I start, what will this do the the existing users within confluence? And if it doesn’t do anything, is it reversible?

My last question is, other than (CUP - Administration Guide 1.14), is there anywhere else I can find documentation on using this product? The information on that link is quite lacking.

Thank you for your interest in our Plugin.
With the next release for our Custom User Profile Plugin this point will be explained in more details. This should be available within the next few weeks.