Wow never mind - the USPS replied finally
After leaving a plaintive reply to the USPS person explaining the situation more fully and that I just needed Active Credentials - I was awaiting a reply. And after posting my post above - I decided to check my email - and here is the reply I just received. I haven't tested this yet.
I am unclear on two things.
1) Am I to be using my testing credentials User Name that the USPS provided me? (I know that I put that in the Settings of the Admin panel.)
2) Why did they give me two URLS? There is only a spot for one URL in the Admin panel.
Reply from USPS - Time elapsed 4 days. (It took 4 days to sort out that WebAssist instructs you to get testing credentials which don't actually work with Power Store 3 - then 3 days for the USPS to finally send this email with the Active credentials info.)
Congratulations on completing your testing using the U.S. Postal
Service's Web Tools Application Program Interfaces (APIs). Your
profile has been updated to allow you access to the Production Servers.
The URLs you will use for the Production Servers are:
Profiles that are inactive for four years will be permanently deleted
If you have any questions, please contact the USPS Internet Customer Care
Center (ICCC). The ICCC is staffed from 7:00AM to 11:00PM Eastern Time.
Telephone: 1-800-344-7779 (7:00AM to 11:00PM ET)
Thank you for helping the U.S. Postal Service provide new Internet services
to our shipping customers.
The Internet Shipping Solutions Team