Yes, that "PayPal Email already in use!" notice means that another account in our system is already using the PayPal Email you're trying to enter in your E-junkie profile screen. Any given PayPal Email can only be used by one E-junkie account at a time, as that's how we line up which E-junkie account's products go with the incoming payment notifications we receive from PayPal.
You can remove the PayPal Email from your other account, which should free it up for use with your subscribed account. If you don't recall the login for that other account, we can look that up for you. Just email our support team to tell us which PayPal Email you wish to use:
View Account Summary just shows which PayPal email is sending us subscription payments for your account, which can be unrelated to the PayPal Email where you are accepting checkout payments from your buyers.