I have the qdslr version v0.3.4.2 (Motorola Moto G) and a Nikon D5300.
I can connect the wifi with the Nikon and it is working.
When I push the Nikon Wifi button in the app than the Nikon dislpay says connecting to mobile device (Verbindung zu mobilem Gerät wird hergestellt). And the the app quits.
With the Nikon app it is working

In the play store is written - fix for D5300, D5500 latest firmware crash
And in the Play store it says app installed.
Now I don't know if the Version in the Play store ist the v0.3.4.3 (does it exist) and the problem is fixed!?!?!
Normally I don't want to pay again the 10€...not cool but if the problem is fixed I mayba think about it!
Thanks for the information!