Kobo Sage - Calibre 3.48

I searched for a related topic but couldn't find one which answers my issue.

I have an old iMac (2011) running High Sierra on which is installed calibre 3.48.

As I'm retired and the iMac still works fine I've no intension of buying a new machine. :-)

That means I cannot upgrade Calibre version past 3.48.

I installed the Kobo utilities plugin but the Extended plugin requires a newer version of Calibre.

My old Amazon Paperwhite (6th Generation) connects happily with this Calibre version but I've not been so lucky with the new Kobo Sage.

I tried swithching out a couple of USB-C cables but to no avail.

Has anyone managed to connect a Kobo Sage to Calibre 3.48 or know how I might get it to do so given my setup.

Thanks.