If you have enabled 2FA then this usually involves an authenticator app on a mobile device to generate the 6 digit TOTP code. If you do not have a mobile device then you can possibly use an authenticator extension in Firefox, but this is obviously less secure. *https://addons.mozilla.org/firefox/search/?type=extension&q=authenticator ---- *https://support.mozilla.org/en-US/kb/secure-firefox-account-two-step-authentication *https://support.mozilla.org/en-US/kb/what-if-im-locked-out-two-step-authentication