Pf,
Thank you for including the details of the error! It looks like there was already a version of Microsoft .NET on your computer, but that version was 4.0.3. Since there was a version of .NET, this explains the message you received when you tried to install .NET 4.7.2, and 4.7.2 wasn't installed. In this case though, Aras Innovator expects the later version. I would uninstall .NET, then once it's clean install 4.7.2. If that fails, I suspect troubleshooting that failure before proceeding with the Aras Innovator install will be more successful.
Especially if you haven't do anything other than install it, I would anticipate that uninstalling Aras Innovator before installing .NET 4.7.2 and then reinstalling them in order would help. Since Aras Innovator relies on .NET 4.7.2, it's just good practice.
Skyler C.