Hey @SCB
Hope you are doing well!
It's a medium effort and it involves participation from Adobe Audience Manager support or account management team.
Here's a detailed document on this subject: Import Google Campaign Manager Data Files Into Audience Manager
There's a little bit of work around Google Cloud storage bucket (step 4 in above link), for which you may reach out to your DCM account manager or support team, if you are stuck. Otherwise, it's a pretty smooth process to execute!
Hope this helps!
Best,
Kishore