When you need to use your General Custom Domain, just log in to the software through it and grab/copy the campaign from URL of your campaigns.
However, if your directory has its own separate custom domain that is set up in its Properties, you don't need to login to that directory's custom domain. Just grab the directory's custom domain straight away and it's good to go. You can do this even when you're logged into the software through Coupon Reach's default domain (app.couponreach.co/login).
If you don't know how to set up the custom domain for your directories separately, check out this article.