To share any file ( or folder), locate the item and find sharing option on the context menu.
Once you click "Share with Fileflex" you are asked to provide details for the share
Provide the share details and click Done and file(s) or folder(s) is shared with other users.
To know more about Share permission and other settings, click here to read: https://help.fileflex.com/feh/en/working-in-the-my-content-tab/how-to-share-files