Can't figure out how to make a Harbinger

Driving myself insane trying to figure out how to choose this spec. Any ideas?

Do you mean that it is locked? The Harbinger soul is a part of the Storm Legion expansion.

When looking at the souls harbinger is simply not there. I think I have the expansion. How can I verify?

I figured out what was wrong. I have two installs. One is on my C drive the other on my SSD. The SSD version wasn't recognized as the default install. Logged in with the C version and was able to see Harbinger!