1. Login to Plesk control panel as admin user and go to the intended subscription.
2. Within the subscription, click on the Users tab.
3. Inside Users tab click on Create User Account link.
4. In the Create User Account dialog, enter the account name login id. Select Application User as user role and select the domain for access to subscription.
5. Now login to the Plesk panel using this new user id and password. Then click on Upload Files button.
6. In the upload files dialog browse the file and select Shared Files for upload and click the upload file.
7. As the upload is finished, the uploaded file can be seen on right side and it can be accessed by other Application users.
8. By clicking on the small folder icon on the right side, the URL for the shared folder and access credentials can be fond, as shown in the screenshot bellow.
9. To change the login credentials for accessing the folder, click on Change credentials link as shown in the above screenshot.