Hi,
This topic indeed talks about the CSV import plugin because that error comes from that plugin and not from the google products plugin.
So the google products plugin doesn't log any error in your case.
So you should find the XML file from google products in /your/website/root/public/hikashop.xml
Note that you've configured your plugin to only process once a day (frequency parameter). So if the plugin was triggered before you entered the filename or path, it's possible that the file might be missing if less than 24h has passed.
For your tests, I would recommend reducing the frequency.