[Hustle] Hustle form not working

Dear support team,

I have a mailchimp form on the page, using Hustle.

https://www.groupe-quinze-gp.com/category/patrimoine/#contact

1) This form doesn't work. Could you please tell me more about this error ? "Oups, something went wrong".
I granted support access, so you may have a look at it.
Is it related to MailChimp's field names ?

As I can upload an image here nor paste code, I'll put more info on a second message underneath.

2) How may I double check that Hustle passes GDPR info to MailChimp (proof and date of consent) ?

3) I would also like Hustle to save into MailChimp the URL from which a user subscribe. Is there a native option to do so ? Or maybe an hidden field ?

Thank you very much for your help.

Greg