This error means that Amavis was not installed correctly. Try running the Warden from the command line and check for any errors:
Centos/RHEL/CloudLinux/AlmaLinux
/usr/local/psa/admin/bin/modules/warden/install.sh
Debian/Ubuntu
/opt/psa/admin/bin/modules/warden/install.sh
If it runs successfully and you don't see any errors then go though the setup wizard again and it should allow you to proceed though the setup wizard.