rpm is not signed when trying to install

I'm new to linux and wanted to install a 3d cad software. I found one in google for linux so I downloaded the rpm to my Downloads folder. I'm use to just installing software through the manager so I had to look up how to install an rpm from command prompt.

After becoming root and getting to the folder where I downloaded the rpm I did a yum install with the name of the rpm. It started to install but then I got:

Package BricsCAD-V13.1.19-2-en_US.rpm is not signed

What does this mean?

Thanks