Firefox version 115 is the last supported Firefox version for users of Windows 7, Windows 8 and Windows 8.1. If you have been using Firefox on these versions of Windows, you will be moved to the Firefox Extended Support Release (ESR) channel by an application update.
If you want to install Firefox on Windows 7, Windows 8 or Windows 8.1 and you visit the Firefox download page at
https://www.mozilla.org/firefox/windows/ your Windows version will be detected and you will be prompted to download the latest Firefox 115 ESR version for your 32-bit or 64-bit Windows system.
Mozilla will provide security updates for Firefox 115 ESR until at least March 2025, when the position will be re-evaluated.