There are two different versions of SpiderOak ONE and Groups for Mac: one for computers running 10.13 High Sierra, and another for computers running 10.12 Sierra or earlier. Having two versions is an unfortunate necessity due to the changes made between Sierra and High Sierra.
The two versions are not cross-compatible. If you are running ONE/Groups on Sierra, then later upgrade your computer to High Sierra, the ONE/Groups application you had will no longer launch properly. You will need to uninstall it, download the version of SpiderOak ONE or Groups for High Sierra, and re-install the application using the new installer. The different installers can be found on our download pages for ONE and Groups.
Some people have more than one Mac and choose to upgrade them to High Sierra one at a time. SpiderOak ONE or Groups will have no problem with you doing that and having (for example) the High Sierra version of ONE on the computer that you have upgraded to Mac 10.13 and at the same time the Sierra of ONE on the computer that is still running Mac 10.12.
One change that Mac 10.13 High Sierra brings is to upgrade your computer's filesystem from HFS+ to the new APFS. The way the filesystem is changed means that all of your files' modification times will be changed, and that in turn will trigger SpiderOak ONE and Groups to rescan all of those files. Depending upon how much data SpiderOak is watching, you may expect this rescan to take a long time and consume considerable computer resources as it does so. This is not a bug in SpiderOak. Indeed, to do its job a backup product should notice modification time changes and rescan when that happens. This is an expected side effect of upgrading a filesystem.
Timestamps also determine which version of a synchronized file is newer. If upon upgrading a computer to High Sierra you find that some of your files have been reverted to a previous version, this would be the cause. SpiderOak ONE and Groups save previous versions of your files, so the wanted versions are not lost. To recover them, see Recovering Versions of a File. Advanced users comfortable with the command line might prefer to restore entire folders with Restoring Your Data With Point in Time. Again, this is not a problem with SpiderOak; it is a result of upgrading the filesystem.
To minimize sync problems, be sure to always keep your SpiderOak ONE and Groups devices up to date.
Some users have reported a warning message from third party security applications. This is a separate matter that is discussed at Little Snitch and 6.4.0 Code Signing.
Other users report that the Sierra or High Sierra firewall never learns to trust SpiderOak ONE or Groups. This too is a separate matter that is discussed at Firewall Never Learns to Accept ONE or Groups.