.NET framework: What operating system? The manual describes in each version what .NET framework is needed.
For .NET 2.0: It is included in Windows 7. And have to be installed on XP from file. And the .NET 3.5 has to be enabled in the Windows features in Win 8, 8.1 and 10.
For .NET 4.0: It has to be installed from file on XP, 7. And it is part of the Win 8.,8.1 and 10 Operating systems, so on these it does not have to be installed.
Furthermore .NET 4.0 framework is backwards compatible with all .NET4.x versions where x is a number, this means that for example if .NET 4.6 is installed on a PC then the .NET 4.0 UCCNC will run without the .NET 4.0 framework installed.
OpenGL: OpenGL is just a recommendation, a standard for 3D accelerated graphics. It is not software, but it is a recommendation about how 3D accelerated graphics should work on computers.
Graphics cards manufacturers concretize those recommendations and building software implementations following the recommendation and putting that into their graphics card chipsets and building driver software which supports those chipset codes on different operating systems (e.g. Windows).
Because OpenGL is not a software you can't download it and because it is built into your graphics card, flashed into a chip on the card you can't update it. The OpenGL what your graphics card have is permanent, you can't update it. If your card has for example OpenGL definition 1.5 then it will always have that, you can't install a newer version.
If your graphics card driver is not installed then the problem is that Windows will not know how to use the card for graphics acceleration. Windows will be unable to use graphics acceleration, because it does not know the OpenGL capabilities of the card and it can't talk the OpenGL language with the card, because the software (the drivers with the OpenGL functions definitions) is missing.
So, then when Windows asks the card about it's OpenGL capabilities like about the OpenGL version it can use with Windows then the card will tell OpenGL 1.0 or 1.1, because it sees that there are no drivers on the computer which supports higher OpenGL version functions and so it can only talk the basic 1.0 or 1.1 OpenGL language with Windows because those are part of the OSes. And so then the UCCNC will not work, because it requires OpenGL 1.3 or higher.
OpenGL 1.3 is very old, it was released in 1999, so any newer graphics card will work with the UCCNC, but the card graphics drivers have to be installed for the above mentioned reason.
I hope my description makes these things clear.