Forum integration & Automatic promoting of users

Hello, so I was looking in to making this myself, but have had some trouble with doing so.
What I want is the following:

Forum integration with the server, so for example, when they join the server, they are asked to log in to an existing forum account. Or they can choose to make one if they don’t already have one.
-Ofcourse they would only have to log in once, and when they have logged in that once, the popup won’t appear to them again.

I also want so, when users donate, they automatically get promoted to the donator group and get all the donator benefits instantly, or atleast almost instantly.

If it’s needed, the forum I’m using is Invision Power, the admin addon I’m using is ULX.

If it comes down to it, I’d be willing to pay to have this done, except I cannot pay through Paypal, but I think I can pay through anything else.
I get an error when trying to pay with Paypal, an error saying something about my card can’t be used for this transaction.
I can use it everywhere else though.

There are no public addons/codes for this at the moment; Forumsync shouldn’t be that hard but knowing how to use Paypal API might be a bit different.

Chances are, you’re going to have to pay somebody.

Did you try gForum? Also you can promote users when they pay a specific amount if you have IP.Nexus (also made by Invision Power)
Link to gForum:

The Paypal API… Oh boy. If you want convenience I would suggest using Google Wallet, the API is a lot easier to use and Google don’t steal your money like Paypal do. C:

However many more people uses PayPal. But indeed PayPals API…

SFM also has a built in subscription thing with group settings.