TL;DR just show me how to install.
This app is an unofficial linux client for whatsapp web that can minimize to tray. It powered by PyQt5. On Ubuntu, we dont have a good whatsapp client. I realized this deficiency and developed this client in one day. I'm using this client and hopefully it would be useful for you.
Yes, I published it under GNU GPLv3. So, you can upgrade source code.
Download package, open a terminal on that directory, and write command below:
sudo ./install.sh