To "get" Shader Model 6.0, you need a combination of compatible hardware (GPU), the latest Windows updates, and current graphics drivers. How to "Update" to Shader Model 6.0
Shader Model 6.0 is not a standalone download.
SM6.0 is not a download—it’s a feature level. Keep your system updated, and you already have it.
In short, if a game requires Shader Model 6.0, it is using advanced calculation methods that older hardware simply cannot physically process.