Windows detected a threat when I tried to download and install Rehearsal Live Share. Why is this?

As RLS is fairly new, Windows has yet to whitelist it. Rest assured, we have reached out to them and they're looking into it. For now, if you're getting threat notices via Microsoft Edge browser about RLS you'll need to click through the warnings to allow the download to finish - see the attached screenshot below. If you're just getting threat notices via Windows Defender SmartScreen after download and during install, here's how to get past it.