Hi Pasquale,
We are unfortunately unable to provide support through our Pre-Sales forum channel, but you can head over to The Events Calendar WordPress.org support forums for assistance and answers.
If you have a PRO license, you can log into your account and get assistance through the PRO forums. If you need to reset your password, you can do so here. This will send an email to the account used when you initially registered for the support forums.
To get you started, you can create categories for the users and assign the appropriate category to a user’s events. Then you can view the calendar of the users on this URL:
http://domain.com/events/category/{category-slug}
Thanks for understanding and good luck resolving your issue.
Cheers,
Andras