Run in terminal:
wget -O TimeTrackerApp.flatpak https://timetracker.empesol.com/files/TimeTrackerApp.flatpak && flatpak install --user -y TimeTrackerApp.flatpak
If you can't find app in menu restart computer or run in terminal:
flatpak run com.empesol.timetracker
To remove app run in terminal:
flatpak uninstall com.empesol.timetracker