For creating the USPS account Click on the website link website
Steps to create an account:
1. Choose language & username
2. Enter Security information
3. Choose your account type as Business Account
4. Enter Account information
5. Find your business address
-After creating your account you have to get the User id and password which is required for USPS configuration
-Find below link for getting user is and password
Link
After the visited the link you will have the Id and Password with email. So enter the credentials in below setting