When a provider is trying to add their payment details sometimes this error appears:
There is something wrong with the payment system setup in this marketplace: the platform has not been registered. Please contact the team to let them know that they should register their platform at Stripe.
This error comes from the platform not being properly registered with Stripe.
How to register your platform with Stripe
To solve this error follow the instructions for “Register your platform with Stripe Connect” in the Stripe setup article. The instructions are almost half way down in the article.