The image you posted indicates that it is trying to roll back .net framework. This usually happens when you are trying to install and older version while a newer version is already installed. Have you tried to completely remove .net then install?
https://knowledge.autodesk.com/support/autocad/...
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
I didn't find any .net framework listed in the "Programs and Features"(from the Windows Control Panel). Your link also says the same for Windows 8.1 as shown below:-
I also checked in "View installed updates" as written above. But I didn't find anything related to Microsoft .NET. Here is what I see there:-
What can I do now?
Regards