Retrieving users data from websites [closed]

There is a language practice site that I use, and every user there has an id, for example (id: 50a56k097). And someone there retrieved the user data and knew the previous usernames of these ids if they changed them. My question is, how can I do this? How can I extract user data from this site easily?I’ve heard about webscraper but dont know how to use it

or is there any script to do that ?

I tried everything to do that but couldnt find the way