I am looking to do something similar as well.
How would you make it so that when a user logs in, like Lewke said, a page is automatically created. Then that page is restricted to only that user when they are logged in. I found this:
https://www.ads-software.com/support/topic/my-crack-at-a-client-login-sectioncustomer-portal?replies=15
But it seems a bit bulky and hasn’t been changed in 3 years.
Thanks!