Registered Users for MarketPress

Since I'm still fairly new to MarketPress and haven't yet had one of my sites go live yet, I notice that if I'm not logged in, I am offered the opportunity to login and checkout (assuming I am logged out).

Am I missing something here? Am I supposed to pre-register users to the cart if I want to? (I notice an option in settings).

That being the case, how do I register users? Do I use the standard wordpress registration?

Apologies for having a pea-brain this morning!

Regards, Callum