I just went through this process, and the same thing happened to me. We have a new rental property in DC (we don't live in DC) , and I wanted to submit the DC tax forms. I was also only given the instruction sheet and no actual tax form to file. I asked support for help and was directed to this email chain. On another note, I was also told that the $64 I spent for a DC tax form (which I didn't receive) was ineligible for a product return since I filed online. The satisfaction guarantee doesn't cover online filing. Interesting.
Anyway, the advice given here seems to be incorrect. When I visited mytaxDC, I learned that you need to file a D-30 form (which you can do online). There is a minimum business tax of $250 for businesses that earn less than $1M. And, if you earn less than $12K in a year, you can file a D-30N affidavit online. So, there are forms to be filed. Turbo Tax just doesn't provide them to you. The "non-resident" form is something you fill out if you think you should get a refund. It doesn't have anything to do with any business taxes you may owe in DC and seemed to be totally irrelevant for what we needed.
Good luck!
