Unless you are using completely outdated hardware that doesn't have a GPU, there is really no reason to install WMM 2.6. If you are just looking for the functionality of the "classic" Windows Movie Maker, I suggest you install WMM 6.0. It has the same look as WMM 2.6, but has both 32-bit and 64-bit versions as well as using the GPU to improve the speed of rendering. WMM 2.6 was designed back in the Windows Vista era for people that didn't have a good GPU. But most people have a capable GPU even if it is onboard Intel graphics that WMM can use.
Installing Windows Movie Maker 6.0 on Windows 7, 8, 8.1 or 10