I've gone through this problem for a few years with new Macs without seeing any resolution on here. I found this firmware update on Fujitsu's website that solves two problems. 1. I get a functioning $400+ scanner back. 2. It solves the 64 bit macOS problem for future macOS versions. It's a firmware upgrade that changes the Evernote edition into a regular ix500. WARNING, you lose some of the automation between the ScanSnap and Evernote, but this page explains what the losses are before you decide to upgrade the firmware.
http://scansnap.fujitsu.com/global/evernote/index.html