Member join form error

Hi all - I’m using memberstack and webflow together, that’s more for context, with my ‘join’ form, when I test it to check a member cannot re-register with the same email, it works notifying them a member already exists (great!), but then I have made a mistake whereby a loading spinning wheel takes over the page and you cannot click anything. For the person to proceed they have to manually click off the page.

What have I done to cause this error?

Here’s the link
https://preview.webflow.com/preview/syncingminds?utm_medium=preview_link&utm_source=designer&utm_content=syncingminds&preview=ba7562356544a1b762a36910f8767e9f&pageId=65c37ec2fcef2f7c3bbf2075&locale=en&workflow=preview

Ive attached a screenshot also, not sure ho useful.