The Vuescan option has already been mentioned. There is also fScanX Home Edition, which is specifically supporting the old ScanSnap scanners. I have not tested this software, but it is on the Mac AppStore, which gives it certainly some credibility.
I have a fi-5110-EOXM, bought in 2006 (!) and it is still happily scanning away. A fantastic device. Fujitsu has not made new drivers for years, but the final version still works. Catalina will bring an end to that. At that point I will either check out Vuescan or fScanX, or, will use an old iMac in my office as my official “32-bit legacy” machine. Scanning into a folder on Dropbox or iCloud, the files will right away be available on my main laptop.
Concerning a previous comment about ScanSnap integration into DT: Even though I have both, I always scan external to DT, and then import. But if you want good integration (say because you have a lot of files coming in), and Vuescan/fScanX can’t be integrated, you could use Finder Folder Actions and set things up such that the folders in which Vuescan/fScanX dump by default, are automatically sending the files to the DT Inbox. DT OCR could then right away work on them. Maybe not as good as full integration, but pretty close, no?