How do new members activate their accounts?

This may be because I am testing it within a Paypal sandbox environment and also developing locally so I'm not sure, but I would expect the user to receive an email where they click a link to activate? If so, I don't appear to be receiving it.

This is what I'm doing:

1. Step 1 - I fill out the register form (username, email, password) and click "register my account".

2. Step 2 - On the next screen I subscribe to my desired subscription plan and pay for the subscription on the paypal sandbox site. The purchase is successful and I can return to the site if need be.

After paying on the Paypal side of things, nothing really happens. If i go to "Edit members" in the plugin, I can see that the user I signed up as is "Inactive", and if I also visit the WP users page I see the user as a "subscriber". The only email I receive is the standard WP one from signing up as a subscriber.

So is there another email that should come?