Encountered the same error when trying to install the addon on mac (not M1), what helped is to use the Anki 2.1.49
version (dmg be found here), not the ideal solution but unblocks the usage of addon.
@Bent if 100% reproducible for Mac on Anki >2.1.49
, this could be a big issue for new first-time Mac users that will install the most recent version of Anki.