There is still a way to get this working, if you install applications manually (not from Google Play store). To get this working, you can install our Phone calls plugin, but you need to install .apk file manually.
You can download .apk file from here.
Once it is downloaded, you need to install it. Usually you can do this by opening some file manager, find the .apk file and click on it. Most likely it will inform you, that the app does not have permissions to install .apk files and it will offer an option to change this.
Once the plugin is successfully installed, go back to ManicTime application and phone calls should be visible.