I was facing the same issue earlier today - are you from Brazil by any chance? If so, this might be happening because the community plugins install script is downloaded as a raw file from github, and lately some LatAM have been having some issues with rate limited requests that are preventing these from working. As a workaround, you could setup a VPN to another country (I suggest Canada as I'm using that on Proton VPN without issues), that should be enough for the script to work.