Adobe Sign trial cannot invite key emails

It's impossible to invite any email on our domain because almost everyone has a free account. How am I supposed to actually trial a product when I can't invite the emails from the domain I control? I've attempted to 'claim my domain' but that requires talking to support that Adobe sees fit to completly block trial accounts from accessing. I've never had a harder time trying to test something. 

Please, how can claim my domain and invite the actual users that we'd be using on this system?

thanks