I want to update Edge Legacy, but can't get to the source code.

Hey comrade! I  like to use Edge legacy, so much so that I went back to Windows 10 Redstone 4 and turned off all of the update stuff to use it. I am aware of the security risks of this! I wanted to update Edge Legacy with some new personalized stuff and possibly some security stuff later, but I couldn't get to the source code, which is most likely HTML due to it being an executable. Please help