This week Fujitsu surprised everyone by releasing new software that allows older scanners to work with OSX Catalina. The software is 64 bit and works works in MacOS 10.15, it supports older models like the ScanSnap S1500, and it fully integrates with Devonthink Pro. Thankyou Fujitsu!
It took me a while to get my canon scanner working under Lion. The trick is that there are two programs that you need to install – the scanner program and the driver. This works for Leopard and Snow Leopard too.