How do I resolve the Mac GlobalProtect VPN client stuck in connecting state?

Issue

After installing the Mac GlobalProtect client, the client never connects and stalls ("spins") in a connecting state

Solution

macOS High Sierra 10.13 introduced a new security feature that requires manual user approval before loading new third-party kernel extensions. You can check to see if the Palo Alto application is being blocked in Settings > Security & Privacy

Look for a message at the bottom of the window stating "System software from developer Palo Alto Networks was blocked from loading."
Select "Click the lock to make changes" You may need to provide the username and password of an administrative user on your Mac. If this is a EWU-owned Mac, see this article to see how to give yourself administrative rights: https://support.ewu.edu/support/solutions/articles/10000042816
Click the Allow button