Can't get my blogs mu theme to appear on my sub domain website

New to WPMU. Just changed my main wp site to multisite. The site where I want to set up a community is not the main domain (careergamechanger.com), but a sub domain -pro.careergamechanger.com is where I want to establish a community with blogsmu theme.

The blogs mu theme is available for activation within careergamechanger.com themes, but not in the pro.careergamechanger.com theme options. On the window in the theme area it says network themes do not appear in this window.

I can't figure out how to get it to appear as a theme choice at pro.careergamechanger.com.

What am I doing wrong or can you only set up a community on the main domain?

Thanks!
Suz