There is a KB article about similar problems. Have you tried that? -- do this first
https://avid.secure.force.com/pkb/ar...h-Sierra-10-13
The above is just a work around for problems when general security settings are app store only and you missing the installation security alert when installing the driver. Likely it appeared behind another window and auto-dismissed.
Still a problem? Does the card show up at all in the System Information utility? (whether seen as a Avid card or some unclear device).
What do the following commands give in Terminal?
$ ls -ld /Library/Extensions/DigiDal.kext
$ kextstat | grep digidesign
$ kextstat | grep avid
Copy and paste all the above output here including any exact error messages.