Hello Jason, and thank you for posting to our community.
Unfortunately, as of October 4, 2017, ShippingEasy no longer supports using an Endicia account created outside of ShippingEasy. This occurred when we converted our two Endicia account system to the single Endicia account.
At this point you will need to register for a new Endicia account, using the steps in the link below.
We do apologize for any inconvenience.
Thank you and happy shipping!