Firewall on server using CageFS

Hello, I have a site that I can’t get the firewall setup on. I run the auto install but it doesn’t work. I’ve done the manual setup on other hosts so I asked A2 support about that.

This is their reply:

“Unfortunately our servers run under CageFS and it’s not possible to change values using custom php.ini files, and .user.ini and .htaccess values may cause errors or be ignored. This is not a bug or a misconfiguration, it’s by design, and I’m afraid we do not officially support auto_prepend_file on shared or reseller hosting due to the fact that all of our production servers use CageFS. For an alternative plugin that doesn’t require this, I can recommend: https://wordpress.org/plugins/sucuri-scanner/”

I’d rather use Wordfence. Any pointers on how to get the firewall setup?

Thanks.