So what should I do? Upgrade to a newer version, and if so, what is the upgrade path? Do I need to go to 9.7 first and then to another version? What exact files from that firmware download list would I need to download to make that work?
Usually working from a ZD, you can disconnect the AP, put the ZD through its path and the APs then upgrade once to the latest firmware version. I am going to imagine that the standalone can do the same thing as its the same hardware.
ZD path from 9.6.x onward was 18.104.22.168.13
>> 22.214.171.124.17 >> 126.96.36.199.203 >> 9.9x >> 9.12x, but I believe you should be able to make a single jump. Just create a backup of your existing settings should anything go wrong.
Read the doc for the firmware you want to jump to as well, in the case that Ruckus have introduced software support costs etc for standalones at certain version etc. (unsure on this myself, I know it exists for the ZD)
You can upgrade them in a single hop, but DO make a backup prior. We have had some seriously out-of-date APs that defaulted when we dragged them to current, but that hop was 7.0 -> 9.5.1, so it's nowhere near the same.