Hello Gabriele,
It sounds like what would work best for you, understanding that you want to have people sign up for events for free, is the combination of our free The Events Calendar plugin in and the premium (paid) WooCommerce Tickets add-on. You can certainly set the price of “tickets” to zero. That would give you both the ability to limit the number of sign-ups and see a list of attendees. And to be clear, WooCommerce Tickets resides on your website. Your visitors aren’t “sent” anywhere for free tickets. They would only have to bump out to a payment gateway to enter payment information if the tickets had a price.
Let me know if you have any more questions!
— Julie