I have reinstalled the CentOS 7.6.1810 Minimal server (no selections), and does as the Foreman Quickstart Guide says:
yum -y install https://yum.puppet.com/puppet6-release-el-7.noarch.rpm http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm https://yum.theforeman.org/releases/1.22/el7/x86_64/foreman-release.rpm
yum -y install foreman-installer
foreman-installer
Still I’ve got the same error: Could not get default values, check log file at /var/log/foreman-installer/foreman.log for more information
The new log is here.