Where can I find the Bitwarden version for Mac OS 10.15.7? the App Store version requires macOS 12 
@BMPBrother Welcome to the forum!
Unfortunately for you, but no current desktop app version supports MacOS 10:
Okay thank you, but why tell them “Access your sensitive information on ANY device with secure cloud sync.” 
MacOS 10.15.7 was the last security update (July 20, 2022) for 10.15 - that’s three years ago. Such a device can’t be considered secure at all.