Do We Need Application ID for Marketpress For Collecting Fee Only?

A question! Since I'm an admin of Wordpress/Buddypress network, I don't want to create a shop myself using marketpress plugin, but I prefer to charge users who want to create a shop using the plugin such as a certain percentage fee, for an example 2% on top of Paypal's fee. Do I have to get an application ID from Paypal in order for me to be able to collect 2% fee? I thought we only need an email address that Paypal recognizes for transaction to take place?