Can’t seem to register, I fill in the form and the capture, click sign up and it just refreshes the page
Welcome @AnWilco
What OS and Browser are you using please?
I’m going to venture, of course, that you have an AdBlocker or pop-up blocker interfering.
You need to then subscribe to the request for 500 calls. Over the product page, you can find that. You have to provide name to the product. Here’s the snapshot;
I am having the same issue, no Ad-Blocker installed, just couldnt register API with page keeps refreshing
Sometimes the main TfL Oyster site needs you to clear your cookies from the site. Perhaps you could try that?
Tried and no luck 
Have you tried “Another Browser”?