Basically the popup is for the Enhanced Features component of the phone where it allows users to send large files and profile information to their contacts. However the feature will require users to submit personal information such as their phone number, messages, and contacts to Samsung which we can’t blame you if you feel uncomfortable doing it. However it seems that clicking dismiss does nothing.
Now this is very obviously a bug and according to Robert Ray, there seems to be a solution to it and that is users can launch the Contacts app, open your own profile, and disable profile sharing which should be able to stop the popups. That being said there are some users who claim that this just ends up hanging their phones.
Users can also choose the Registered information option to deregister your number which should also disable the popup. This bug does not seem to affect all Galaxy S6 owners so there is a chance you might not be able to replicate it on your phone. No word from Samsung on how to deal with it, but let us know in the comments below if this is something you’re experiencing.