Are we talking about actually copying the files, or about which program's window opens when you insert the camera or SD card, before any files have been copied?
Can you navigate to the camera/card in Opus after it is plugged in, and then copy the files in Opus?
Opus light does not have (and has never had) Explorer Replacement functionality, so it would not automatically open in response to plugging something in, but it should still be able to copy the files.
If your older version is Opus Pro and you bought a separate copy of Opus Light rather than upgrading the older Pro version, that might explain the difference. We may be able to work something out if that's the situation you're in.
There is no ongoing subscription, just a one-off payment.
If you have sales issues, please contact our sales address as we can only deal with technical queries here at the forum. See Common purchasing, upgrading and licensing questions (very first item in the FAQs list).
Google Docs runs inside of a web browser, and Opus isn't involved in that.
If you can drag files into it from File Explorer then the same should be possible from Opus as well, but otherwise the two things don't have much to do with each other.
Please give more detail on exactly what you are trying to do with Google Docs and Opus, in a separate thread. ( Ask one question per thread )