WordPress Subscription REST API Error

Dear sirs,

I installed the Woocommerce activation kit and everything works properly for the normal products.
When I try to activate a subscription product indeed, I receive this error message:

“Failed to use WordPress Subscription REST API. Check the configuration.”

ErrMsg

Activation and validation for normal products works perfectly.

How can I fix it?

Thanks

Marco

P.S. I also submitted a support ticket about this topic. Ticket #3527.