BikeCAD version 13.0 for Windows doesn't actually require that Java be installed on your system. It also shouldn't have any connection to the copy of version 12.5 which is already on your system. If it seems like installing 13 has caused 12.5 not to work, I would encourage you to consider what other operations might have been performed on your system recently as the problem could be due to something else entirely.

Version 13.0 for Windows comes in both a 64 bit version and a 32 bit version. You only need to install one of these on your system. The 64 bit version will only work on a 64 bit operating system. Running the 64 bit version on a 32 bit OS could result in an error message.

While I would like to work towards getting your current copy of version 13 running, there is another option that I think is worth trying. I have added another file to your download links. This file is called: BikeCADPro_13_SetupStream.zip. This file was prepared in the same way that version 12.5 and all previous versions were prepared. Unlike the default version 13.0 which doesn't require that Java be present on your system, this edition of version 13 does require that Java to be installed on your system.

Looking forward to getting this resolved.