Paypal is asking for Webassist's API account username
I trying starting from scratch and creating a new api credential.
The first thing Paypal ask is for an API Accont Username:
Third-party API Instructions
Contact your shopping cart or solution provider for your API account username. Then enter it in the API account username box.
Select the API access categories to which you want to grant permission. The categories include the following APIs:
Reporting and Backoffice APIs
Authorization and Settlement APIs
Other APIs or Permissions
Encrypted Website Payments
Click Save to enable your third-party shopping cart.