Hi Stefano,

Thanks for reaching out to us.

Please, find the answers below

1- Why doesn't the "Settings" tab appear? Is there any way to correct it? I have updated the plugin and it is still the same.

This could be because of the user role permission. Only the admin should have the option to see the settings in the backend, but it could be that you have multiple user roles assigned and this is creating a conflict. Make sure that your WP user has only one user role assigned.

2- In the events section is there any possibility that when registering a person can register 2 or more? But I need the data of all the people to be completed, not just one, meaning that the fields marked in yellow should be repetitive. Could you explain to me how to do it?

This is possible by enabling the "bringing someone with you" option in Event settings. If you configure the capacity to 2 or more, you will see this option.

To collect the information from additional people, you would need to use custom fields. The Custom Fields feature gives you the option to add more fields to your booking form so as to customize it to best match your business needs. The customer’s first and last name, email address, and phone number are there by default, but with the Custom Fields feature you can add extra fields if you want to ask a customer a question, collect additional personal details, or for any other reason.
For appointments, these fields will appear on the Booking form under the default fields, and once your customer fills them this information will be shown in the appointment information on the back-end.

More information on this link.