Trying to install Blender on my Mac and I am being told that I cannot do it with my operating system (macOS 10.10.5). Is it possible?
You can't install the latest version as that requires macOS 10.12 +.
You can install Blender 2.79:
Blender 2.79 runs on all systems that support OpenGL 2.1 and above, with recent graphics drivers. For macOS, version 10.9 and later are supported.