Ajax failed or nonce verification failed.

Hi,

I bought this amazing booking addon. If I access the booking page with my Chrome account everything is fine. If I try to log in from other accounts I get the following error:

“AJAX failed or nonce verification failed. If this error occurs repeatedly, access may be blocked by a security plugin. Try changing the values of “Select the URL for AJAX on the public page” and “Select a function to validate the value of a nonce with AJAX on the public page” in Booking Package > General Settings.”

I tried different combinations in the general settings with no results. How can I solve it? Thanks in advance for your answers!

The page I need help with: [log in to see the link]