Uploading confidential documents

I have an organizational problem that needs a solution.

Let's say I'm organizing a student club event with 200 participants. Under our university policy, all participants must submit a complete compensation form.

However, I do not want to be sent an email (which means I have to read 200 emails). Instead, I want you to upload your indemnification form in a folder / website. In this folder I do not want them to access the compensation forms loaded from other people.

As the "administrator" I can see and download the uploads of all,
but as "participants", they can only upload and see their own compensation form, not anyone else's.

Does anyone know a website or configuration onedrive / google drive that allows it?

Thank you and have a great day ahead.