Cannot enable FIPS on Ubuntu 18.04 Pro on AWS

Hi, I subscribed to the marketplace subscription of Ubuntu Pro 18.04. I get an error about a missing keyfile when trying to enable FIPS.

root@ip-10-142-18-16:/var/snap/amazon-ssm-agent/1566# ua status
SERVICE ENTITLED STATUS DESCRIPTION
cc-eal yes n/a Common Criteria EAL2 Provisioning Packages
cis-audit no — Center for Internet Security Audit Tools
esm-apps yes enabled UA Apps: Extended Security Maintenance
esm-infra yes enabled UA Infra: Extended Security Maintenance
fips yes disabled NIST-certified FIPS modules
fips-updates yes disabled Uncertified security updates to FIPS modules
livepatch yes enabled Canonical Livepatch service

Enable services with: ua enable <service>

                Account: XXXXXXXXXXXX
           Subscription: XXXXXXXXXXXX
            Valid until: n/a
Technical support level: essential

root@ip-10-142-18-16:/var/snap/amazon-ssm-agent/1566# ua enable fips
One moment, checking your subscription first
GPG key '/usr/share/keyrings/ubuntu-fips-keyring.gpg' not found