The reason you got this error is because there was an issue with the internet connection, and because of that you were not able to install the MicrosoftRootAuthority.crl file. The good news is that "It is not necessary to download the MicrosoftRootAuthority.crl file". But if you still want to have this file go to link on the prompt message and download the file.
If you have any issues, let me know.
Good luck
Prateek
