To backup Product Designer App data. You need backup database, upload folders and plugin code
Database #
Please login Cpanel -> phpMyAdmin -> Open Database -> Export tab (1) -> Select format (2) -> Click Export (3) to backup.

Module #
Version 3.x.x.x: Lease login Cpanel -> File manager (or connect FTP) -> Open folder: Opencart root/admin/*/extension/module/productdesignerapp and Opencart root/catalog/*/extension/module/productdesignerapp -> Download to save backup on your computer
*) is folder like controller, model, view
Version 4.x.x.x: Lease login Cpanel -> File manager (or connect FTP) -> Open folder: Opencart root/extension/productdesignerapp -> Download to save backup on your computer
Uploads #
Please login Cpanel -> File manager (or connect FTP) -> Open folder: Opencart root/image/productdesignerapp -> Download to save backup on your computer