Sign up form after payment of certain Items

Hi Everyone,

I am hoping someone has done this or can help as I haven't been able to find a solution yet.

What I am looking to do is have a form that when you purchase certain items in this case a swimming class it has you go to a registration page where you can then register with a form. I would like to have it be easily downloadable kind of like a form tools database where you can export an excel spreadsheet.

I was thinking of just adding it to the thank you page but then it would appear on every purchase and we sell all sorts of wilderness gear.

Does anyone know if there is already a solution or have done something similar.

I appreciate any help.

Thanks,

Chris