I am looking at working on improving an app that has not been updated for several months, add some features etc. In the description of the app on google play it says that the app is open source and links the github, and in another forum it says the same thing (with no proof on the forum that they are the creator).
However, on github there is no license and it does not say it is open source. It does have a link on the github readme to the google play page where it says that the app is open source but it doesn't say on github page that it is open source.
So my question is, can I fork the app? I am not aware of the legal rules, can I use it on my phone and give it to a few friends? Can I share it larger than that or could I even put it on google play? I have tried contacting the creator of the app in multiple places with no response.