Good evening Guglielmo and welcome to the Events Calendar forum!
Thank you for your interest in our products.
We’ll be glad to answer your questions.
Unfortunately, when I create a new RSVP, it is not shown either in backend or frontend. I can not even see the checklist page.
There are a couple of things to check out to fix this.
If you have not already done so, please read the following: https://theeventscalendar.com/knowledgebase/new-user-primer-event-tickets/
Secondly, make sure the correct post types are selected for where tickets can show up under Events -> Settings -> Tickets
Thirdly, please make sure that you have not inserted a start sale date. Until that date is met the tickets will not show up. You can test that by removing the start sale date completely.
Finally, if all else fails I would recommend taking a look at the capacity settings.
Let me know how that goes.
Best regards,
Geoff B.