In general, we do not support beta releases of any operating system, and as of August 2018 macOS 10.14 Mojave remains in beta. That said, we have finished our testing and can confirm that SpiderOak One and Groups for Mac 10.12 Sierra work fine on the current beta of Mac 10.14. While we cannot guarantee that Apple will not make changes to its operating system before its general release, and for that reason we cannot officially support it until then, for now SpiderOak One and Groups run fine on it.
We also have separate versions of One and Groups to use on Mac 10.13 High Sierra, but those do not work on Mac 10.14.
For more information, see our Supported Platforms and Operating Systems article.