An Admin controls whether a User can Download and/or Upload and which folders/files these permissions apply. Within the same Library a User's permissions can vary from folder to folder and file to file.
The User Panel will display different permissions for Users depending on which file/folder you are selected on in the Library.
Change these permissions with the icons adjacent to that User -
Select the Up Arrow to grant Upload permission
Select the Down Arrow to grant Download permission
Select the Link Icon to grant both Upload and Download permission
Icons will appear in green when they are activated.
To remove permissions select the User/Users then select any or all of the Icons again to turn them off.
When a folder/file is selected the list in the User Panel directly reflects User's active permissions specific to that selected folder/file.
NOTE: Permissions that apply to a "parent" folder also apply to all included subfolders.