Although spideroak installs okay (12.1-RELEASE-p3), setup (registering with SpiderOak's cloud servers) fails with 'certificate verify failed'. Completing setup is needed for all useful operations.
This package is an unofficial (not distributed by SpiderOak) freebsd port of SpiderOak's Linux client. At this time, the pkg uses SpiderOak version 6.0.1 and SpiderOak is distributing version 7.5.0. Here's their explanation of this error https://spideroak.support/hc/en-us/articles/115005874603-SSL-Certificate-Verification-Error.
The tldr version is the package includes a certificate that is out of date.
I did not participate in this freenas discussion, but it describes the problem and a workaround: https://www.ixsystems.com/community/threads/spideroak-help-fix-certificate-verify-failed-error-and-getting-spideroakone-7-2-0-working.69492/
I followed the procedure replacing some of the pkg-installed files with current one's from SpiderOak's Linux tarball) and setup works.
I have a SpiderOak paid account and can test an updated pkg.