You can leverage Google Drive to access files while using AppStream. We would recommend using Google Drive whenever you save or use files in AppStream.
After logging AppStream, and launching a Desktop/Application, look for the large white band at the top of the window.
In the top band, click on "My Files".
In the window that opens, select "Add Storage" in the top right corner.
Select "Google Drive".
In the window that opens, sign-in to your SNC Google account.
Click "Allow" when asked if you would like AppStream to have some control of your Google Drive.
Once setup, you'll be able to see "Google Drive" in Windows Explorer windows. You can open files from Google Drive, and save files to your Google Drive from any application you have access to in AppStream. You also have the ability to access Shared Drives and Folders.