Since the MacTeX-2021 package does not support my old OS version I have manually installed TeX Live 2021 via the Unix installer as described on Unix Install of TeX Live 2021. The installation worked fine, but the second step that would configure TeX so TeX Live Utility and various GUI programs can find it fails, because the installer of TeXDist-2021 says "TeXDist-2021.pkg can't be installed because its digital signature is invalid". I have redownloaded that pkg several times and also tried mactex-texdist-20210226.pkg from CTAN with the same outcome. I'm pretty sure the signature is fine and it's my side that poses the problem, which is kinda corroborated by this. But that would also mean I can't really "fix" this signature problem I guess.
Right now TLU doesn't see/show the new version (neither in the prefpane nor in TLU itself). Is there maybe a way I could manually do what TeXDist-2021 would do?
Help is much appreciated!