Modified use cases to see the interaction as mermaid.
Use Case 1 : No Authentication , upload
From his PC the user will have a powershell to send $PROFILE.CurrentUserCurrentHost and current user name [Environment]::UserName and PC name [Environment]::MachineName to the site ( see Use Case 3) . The username and all data will be deleted after 30 days . The powershell should be of max 4 MB size.
Use case 30: User can see data
User can the page /userName/ the PC(s) with a link to download the file and a powershell to execute that will overwrite on his new PC the $PROFILE.CurrentUserCurrentHost
Use case 4: List of users
User can the page /u and find the list of all users.