Hi Imad,
I havn't Portal to host event website, but I thought it could be easily achieved by customization with code.
I have made a customization that add a customized tab in before, these tab elements are located in event.registration.html.
In the process, I found that those tabs display are controlled by Event API back-end,
as Pass information for example, it's controlled by showPasses variable.
Then in event.component.ts, the variable is boolean type.
the pass information tab will appear if callback data from Event API back-end has valid pass information for current event.
Now we know how to control the tab display, in your scenario,
you could define a boolean variable userAuthenticated, and by default is false:
add condition that whether user has logged to set the variable to true, and associate the variable to showPasses,
then only user who has logged could see the Pass information tab.(my screenshot code is just demo)
Due to my event website hasn't sign in feature, so you could read articles below to get current user information, then replace my demo code with user identity request code.
Article 1 revealed that liquid js is still available in event portal, so you could try to use " '{{ user.Id }}'; " to get whether user has logged.
https://pkoval.com/2019/04/07/extending-dynamics-marketing-event-management-portals/
Or try to request Event own api to get logged user information: GET/users/authenticated
https://docs.microsoft.com/en-us/dynamics365/marketing/developer/user-authentication-events-api#retrieving-information-of-authenticated-user
You can find all event api in the doc.
Regards,
Clofly
