Instance types for R80.20 or higher:

• Checkpoint Gateway: c5.large  (2 vCPU / 4 GB) or c5.xlarge (4 vCPU / 8 GB)
• Checkpoint Manager: m5.large ( 2vCPU / 8 GB) or m5.xlarge ( 4 vCPU / 16 GB)

Once launched, SSH in and set a temporary admin password:

$ ssh -i ~/.ssh/mykey.pem admin@10.10.10.123
This system is for authorized use only.
In order to configure your system, please access the Web UI and finish the First Time Wizard.

gw-f0633c> set user admin password
New password:
Verify new password:
gw-f0633c> save config

I also like to add routes so the Internal interface is accessible:

gw-f0633c> set static-route 10.0.0.0/8 nexthop gateway address 10.10.10.1 on
gw-f0633c> set static-route 172.16.0.0/12 nexthop gateway address 10.10.10.1 on
gw-f0633c> set static-route 192.168.0.0/16 nexthop gateway address 10.10.10.1 on
gw-f0633c> save config

Now access the GUI.  In this case, https://10.10.10.123