> The free plan on overleaf only allows collaboration between 2 people. If you have 3 students in your report assignment then you can't use overleaf for free.
Yup. You used to be able to share projects with unlimited people via link sharing, but they annoyingly got rid of that last year [0]. And Overleaf's cheapest plan is still more expensive than a basic VPS, so it's actually cheaper to self-host (which is what I'm doing [1]).
> That sounds like a sign that overleaf is struggling, that they had to make that change.
Either struggling or realized that they have a captive audience—if your professor requires assignments to be typeset with LaTeX and assigns group projects, there aren't really any other options.
[0] https://www.overleaf.com/blog/changes-to-project-sharing