Once your application is completely functional, you email them (lol) and then they go through contract negotiation and application/security/etc. review where you get your terms.
Isn't this just a way to filter out the type of clients they don't want. If you do not have the time or resource to go through these bureaucratic scenarios, then you aren't a good fit.
Sure, but they're not going to even tell you if you're a good fit until you go through the entire expense of building for their gateway. I'd think one would spend that effort integrating with any number of other gateways that have some clear requirements. There's just no clear advantage here that I can see.
But...why would anyone tolerate that when there are so many other services out there? Maybe they have some competitive advantage, but their site sure doesn't make it clear what it is.