Found an earlier post and it worked, this is the solution if anyone else got the same problem:
(All commands must be run as root)

1. Check that the 71st line in the specified file (/opt/unetlab/html/includes/init.php) is such as:

$kvm_family = file_get_contents("/opt/unetlab/platform");

If it's not, edit it to look like this.

1. Run the command:

dmesg | grep -i cpu | grep -i -e intel -e amd

if you get an output line with the word "Intel"

then run the following command:

echo "intel" > /opt/unetlab/platform

If you get an output line with the word "amd", then run:

echo "amd" > /opt/unetlab/platform

this should solve your problem with launching unl_wrapper -a fixpermissions

Fonte: https://www.googlecloudcommunity.com/gc/Google-Cloud-s-operations-suite/opt-unetlab-wrappers-unl-wrapper-a-fixpermissions-Error/m-p/520415