This is an update to the previous CentOS installation of OSSEC 3.6 ( here https://cheesefather.com/2020/06/install-ossim-ossec-agent-centos-7/), updating it to 3.7. You need one more library installed before OSSEC can update:
dnf -y install systemd-devel
wget https://github.com/ossec/ossec-hids/archive/3.7.0.tar.gz
tar xzf 3.7.0.tar.gz
cd ossec-hids-3.7.0/
./install.sh
Or to install from scratch, just change the first command and add the other requirements:
dnf -y install libevent-devel pcre2-devel openssl-devel systemd-devel