So with Clust you can 3 things with files:
You can collect files (from recipients)
You can send files (to recipients) -Sharing is both ways basically
You can share files (with stakeholders)-
You can add private files to your application
Yes, Files format and sizes can be customized in your account (tuto here). Yes folders are shared accross your team, not externally (clients, recipients, stakeholders). They just allow you to stay organized. (More about folders here)
Go to our product roadmap to tell us more on what you exactly want about this feature.