Fred,

Thanks for asking this. I understand this is probably a bit unfamiliar for starters. I admit, this is unfamiliar with me. I decided to investigate and hunt down the info.

Here's what I got:
User name, if used. PayPal Manager allows an administrator to assign a user name to each individual who has access to PayPal Manager. If no users have been created, leave the field blank. Also, if you are logging in as an administrator for the first time, this field will be blank.
Partner name that was provided to you in your welcome email.
Password that you created during registration, or that was created by the administrator on the account.
(SOURCE)

I also called PayPal and navigated their phone tree, transfered three times and finally got to someone who more or less explained this to me.

The guy I spoke with suggested this information is found on the invoice and email communications from PayPal to the Payflow Pro account holder.

He advised if account holders don't know what to put into the fields, they can contact Payflow Pro Support at 1-888-883-9770 for assistance. It's suggested to have login name, full name, payment method, etc. ready so they can verify and provide these credentials.

I hope this helps Infusionsoft users with their PayPal Payflow Pro merchant gateway integration.

~Joe