Under System Preferences / Network, press the + symbol at the bottom of the network list on the left and enter the values shown in the screenshot below.
Enter the Server Address shown below, and your Active Directory credentials in the Account Name and Password fields.
Press the Authentication Settings button and enter the Group Name as shown below, and the Shared Secret saved as Palo Alto IPSec VPN group credentials in 1Password. Then press OK.
Press the Connect button.