Next step in finding places where my potential clients hang out

Hello Everyone,

So I have a new business idea. I really think it could be something. This time in stead of diving into coding right away I first started testing my Idea.

My idea is to make an app for  residents of appartment buildings. In our country it is the law that every appartment owner has  to pay a monthly fee to save money for maintenance costs.  Usually a company is paid to take care of the management and service of the building. And a board is formed by appartment owners who are in charge and responsible.

Personally I have a negative experience with these companies as they cost a lot of money and they really don't do well. A second problem is that lots of owners are really not coorperative and don't really care what happens wit their money and building.

So with my app I want to attempt to increase involvement of the other owners and stimulate faster handling of the incidents.

No what i have done so far is:

I shared a survey on Facebook which hit me up with 8 responses. I spoke to a board member of a different building whom I showed some wireframes and she was really positive about the whole thing.

So now I started building it and I am well underway. However, i feel that I have lost contact with potential customers. What would be a good next step to keep in contact with my customers and where would I find them? Where would these customers hang out?