You might try the Canon support forum -
https://community.usa.canon.com/t5/Professional-Photo-Printers/bd-p/proprintersThe planned obsolescence of software under Apple is my biggest gripe with them, which is why I now almost exclusively use my Windows PC's rather than my Macs. With just about every Mac OS update Apple ends up essentially disabling older software.
My Windows PC is running Win 10, which came out in 2015 and ALL of my "old" software runs with no issues. My Mac Pro and MacBook Pro are both running High Sierra, which came out in 2017. However I can no longer use TurboTax on either of the Mac computers because they don't make a version compatible with High Sierra. I've stuck with High Sierra because I run CS6 Master Collection and that's the last Mac OS that will support CS6.
I recently bought a Pro 2600 and Canon does not provide a printer driver for it on my High Sierra Macs but does provide a driver for my Win 10 PC that is running a 2 year older OS.
If you can't get the plug-in to work with the newer Mac OS'es you might try Mirage, which has a Mac version. Mirage has a 30 day full featured trial and it supports both the older and newest Mac OS'es.
People have chided me for expecting Canon to support an "old" OS, yet Canon still supports Win 10 (provides a driver), which came out 2 years before High Sierra. Good luck.