Hi,
same issue had/have I, spent some time to investigateor solve, - my solution - needs to proove, but at least successful installed:
On very fresh install
I have added as prerequsite:
yum install centos-release-ansible-29.noarch
my step1:
foreman-installer --scenario katello
(without any other options, plugins)
that successful inmy case
step 2 :
foreman-installer --enable-foreman-plugin-ansible --enable-foreman-proxy-plugin-ansible
where also had some issue with keys thingi, but "You can generate one with ssh-keygen -t rsa -b 4096 -f /usr/share/foreman-proxy/.ssh/id_rsa_foreman_proxy -N ''"
so after added keys, and rerun: success.
step 3 - foreman-installer --enable-foreman-plugin-openscap
step 4 - foreman-installer --enable-foreman-proxy-plugin-openscap
even I had not planned for my testing add ansible plugin, it seems, that solves my issue. (exact same error message as you had ( on exact same OS and foreman version) .
gyokiss