if I fly a dji drone within 3 miles of a regional airport will the app let me even take off? I won't fly over 50 feet.   also, do you think that it is ok to fly low there?

I think you might to be another statistic if you do.
Seriously though, you should contact the airport to see what the score is. Depending on the location you want to fly in you might be able to unlock the zone within the DJI app.
I think about 1.5 miles around the airport is a no fly zone and between that and 5 miles is a restricted zone. Not long ago I planned to get a sunset shot of some old ruins not far from me but there is a military airport not far from a location I wanted to fly. My planned flight was maximum 50m height. I was outside the no-fly but inside the restricted. The app asked me to tick some boxes and accept responsibility and I could fly. I had previously contacted them to let them know the area I would be flying and the max altitude I was flying at. The response was along the lines of, if they had aircraft that low I should be running.
It all went without a hitch. Its just about planning and contacting the right people to let them know what you are doing.

It all depends on the airport classification.  Most smaller airports in the US have a 2 mile no-fly zone and a 5 mile warning zone.  Larger airports may have larger and non circular boundaries.  Check B4UFly app. You may fly within the warning area with notification of the airport ATC (at controlled airports) or airport manager in non-controlled airports.  You're still responsible for safe flight.

Sir, I would not recommend you fly near the airport. If you want to unlock the place, please conact our Flysafe department and ask for the permission of the local airport. Thanks for your understanding.