When running you get this message:

# systemctl enable nfs-server.service
Failed to execute operation: Access denied

Solution is to disable selinux or to allow for proper SELinux rules to allow for the above action:

# vi /etc/sysconfig/selinux
…
SELINUX=disabled
…

# setenforce 0
# getenforce
Permissive

Alternately see the following post for details on how to tailor SELinux rules for similar cases.

Cheers,
TK