Protect sequence of pages with same password for each of two groups of users

I'm currently creating a home page (learning environment) with wordpress. It should serve for an experimental study with two conditions. Based on the condition a participant will be assigned to, he or she should be redirected to one of two different page sequences. This redirection should start after page 10. After clicking through the group specific sequence of pages then, all participants should finally get redirected to shared (group independent) pages again.

So, they start with the same pages, then (I guess) there will be a login page where participants should enter one of two passwords (based on their affiliation to group 1 or 2), then they are going through their group specific pages, then they work through shared pages again.

Could someone please explain how I can realize that? I worked several times through all the forum posts here but there are only contributions about how to set multiple passwords for the same pages instead of the other way round.