Unfortunately, I don't know what platform you're on. So I may tell you how to make team-specific loadouts, but it'll be with the console version (PS4 specifically) of the editor.
Step 1) Go to the loadouts section of the editor.
Step 2) If you're on the PS4, pressing down on the left joystick (or L3) will assign the loadout that you currently have highlighted to either both teams, team 1, or team 2. XB1 is probably similar. Not sure what button you use on PC.
Step 3) To make sure the loadout is properly assigned, check the information panel on the right of the loadout screen. You'll see what team the loadout is assigned to on the bottom of that panel.
That's it. Hopefully it helps!