If you have already entered your shipping info into the checkout page why would you go to PayPal and enter it again there and be sent back to your website to see the shipping charges and then go back to PayPal again, pay for the item and then go back to your website again to confirm the transaction.
This doesn't make any sense at all. It should calculate the shipping before going to PayPal.
As for Payflow Link...
I sent a request for support yesterday. Did it go through? I have all the PayFlow Link info. I tried entering it in the form every different way I could think of and could get that to work properly either.
Login: Is this the main PayPal user account email ? Errors with "Username is required"
Merchant Login: Is this the PayPal Manager username or API username? "Errors with Password is required."
User: Is this the PayPal Manager username? Errors with "Signature is a required field".
Password: Is this the API password or PayPal Manager Password? Or? Password is not a required field.
I have tried many combinations, but haven't been able to get it. Don't know if it is just my misunderstanding of what is required or the extension.