Seriously, whatever you do, you need to spend the same amount of time promoting it, otherwise no one will notice. 50000 downloads is nothing in 5 years, it is 2.7 users a day. If you are in SanFrancisco you can get more than 3 downloads a day just going to the street and talking with strangers.
And they got 2.5M in their series A. https://index.co/company/AppDotNet?utm_source=thenextweb.com
Where were their budget for marketing? At least I would have expected 500k in marketing and 1$ per install, them we can talk about the users not liking the product or whatever.
UPDATE: you can keep downvoting (I would appreciate a feedback comment to explain the downvote) but it doesn't change the fact that marketing is more important than the product and they didn't spend on it