You may have tried to install an update, not a full software version. You actually need to install V6.3L50, then the updates to V6.3L61 and V6.3L70 in sequence.
In the link below, follow the instructions in the section labelled “Workaround”: http://www.fujitsu.com/global/support/products/computing/peripheral/scanners/scansnap/faq/hsierra004.html
Don’t try to navigate Fujitsu’s support website using your ScanSnap model number. The version V6.3L70 in the direct link above works with multiple models of the ScanSnap line of scanners, even though this version was officially designated for another scanner. Fujitsu is transitioning to its new software, “ScanSnap Home”. Several older scanners are no longer supported with this new software, effectively rendering certain scanner models obsolete. Welcome to the “Fujitsu Orphans Club”.
This Fujitsu ScanSnap problem has been discussed extensively in other threads in this forum. I posted a series of links to many of the forum threads in post # 37 of the thread in this link:
https://talk.macpowerusers.com/t/mac-power-users-464-stephen-who/10357/37
Good luck - Hope this helps!