@bumi @feld I think you need to use the beta?
"2024-09-16: GPG Suite beta includes a GPG Mail version that supports the just released macOS Sequoia."
Thanks bumi for reaching out to our support. Glad we were able to figure out, what was preventing activation of GPG Mail and bring your setup into working state.
If you need any additional support you can always reach us at https://support.gpgtools.com ☀️ 🔒 💪