My first problem was that it did not worked, I couldn't build APK. So I contacted the author, he first told me that this must be problem on mi side. So he connected to my PC via Teamviewer to fix my problem remotely. After sometime he said that he will send me next day source code fixed. That happened eventually after 6 days when I was contacting him more times. I was able to build APK but Google has rejected this app because it contains code to facilitate Ad Fraud. I am not programmer so I asked the author if he can help and he said that he doesn't know that I should ask Google, nevertheless also he offered that his paid support can sort this out. So I had to hire external developer to sort this out.