First we are going to become root

sudo su

Next we are going to join the realm. This should installed everything needed after you run the command below

realm join domain.com --user domainadmin

Permit all users to log in.

realm permit --all

Add user group as root

nano /etc/sudoers

Paste into above file

%groupname@domain    ALL=(ALL:ALL) ALL

Allow sssd to create user directory

nano /etc/pam.d/common-session

Paste into above file

session optional        pam_mkhomedir.so skel=/etc/skel umask=077