Unfortunately, Tor Browser 15.0’s minimum support requirements are macOS 10.15 and later. This minimum is set by Mozilla’s support requirements for Firefox ESR 140, on which Tor Browser 15.0 is based.
However, Tor Browser 13.5 legacy – which is based on ESR 115 instead – provides limited support for macOS 10.12 to 10.14. At present, Mozilla are warning that support for ESR 115 will end in February 2026:
Mozilla is providing critical security updates through the Firefox ESR channel up until the end of ESR version 115 in February 2026. After this, no security updates will be provided and you are strongly encouraged to upgrade to a supported macOS version.
To download Tor Browser 13.5 legacy, please see this forum post for details: Download Tor Browser 13.5 legacy on Windows 7, 8 and 8.1 and macOS 10.12, 10.13 and 10.14