Many of the target groups you listed have their own proprietary contract processes/apps in place.

Low hanging fruit may be independent consultants, freelancers, and small business owners. They deal with contracts all the time.

If you are going to continue targetting real estate, financial, and legal firms; take a few hours and interview those you have contact within those fields. I guarantee they have frustrations with their existing program and would give you an ear-full to position your product correctly.

I'd love to help more, if you have another question, or want more specifics, feel free to book a call with some times you are available to connect.

To your success,
-Shaun