I'm not sure what the specific reason is, but I assume that either the USB driver or Odin will not work properly on Windows 7. Best case, it will not even install. Worst case, it works partially and bricks your tablet. I wouldn't recommend to try.
LineageOS is a free, community built, aftermarket firmware distribution of Android 11 (R), which is designed to increase performance and reliability over stock Android for your device.
LineageOS is based on the Android Open Source Project with extra contributions from many people within the Android community. It can be used without any need to have any Google application installed. You will need to provide your own Google Applications package (gapps). LineageOS does still include various hardware-specific code, which is also slowly being open-sourced anyway.
Base source code is available in the LineageOS Github repo. And if you would like to contribute to the project, please visit our Gerrit Code Review.