Is it possible to use Kirby for creating a secure page for documents exchanges (PDF, images, Word doc, etc.) for clients.
The idea is to create a specific client area where I can deposit specific different files of different types and the client can do the same with their login.
When I log to the website as an administrator, I can see all my clients list and upload files to each specific client’s folder.
Each client will have a specific login/password and will be able to access his documents and be able to upload documents as well.
Yes, you could - for example - use a field to determine which user can read/update a particular page; or use individual templates per user. These criteria can then be used to lock access to other content. Note that for a user to access a specific page, the path to that page (i.e. all the parents) must at least be readable (unless you provide a direct link to the page).
You can block access to content on the frontend as well, but then you would have to create the upload functionality for files yourself. Permission events can also be used on the frontend via the $user->can() and $user->cannot() methods.
BTW. You can also use Panel permissions to limit file uploads to certain file types or min/max sizes (or any other file properties)…