To install the Mac FileGuard Beta, download the installer from the link page dialog that appears when you download a file shared with Secure Delivery.
Launch the installer.
Use Touch ID or Enter your password to proceed.
Follow the installer instructions to complete installation of FileGuard. After completion you'll see a dialog below. FileGuard requires the use of system extensions that need to be enabled.
Click OK and follow instructions to enable system extensions.
Click on the lock icon and provide your password or Touch ID, and click 'Allow'. You'll need to restart the computer so that this new system extension can be used and FileGuard can run successfully.
Start the FileGuard program if it is not already running, you should see it appear in your Menu bar.
On first start, you will see a notification like the one above, asking for permission to allow FileGuard to show notifications. Choose Allow from the Options dropdown in this notification.
Click on the FileGuard item in the Menu bar and click on Open FileGuard Folder.
Simply drag and drop files downloaded via Secure Delivery onto the drive to decrypt them. Open the drive to access the decrypted files.