The point to GetFullPath is that for a file in the current folder, or a subfolder of the current folder (ie where the job is running) it will get you the entire path to the file. You don’t use it to get the path of a file that’s outside the current folder.
Is Data\SAS File in your project path? If it is, try “.\Data\SAS File\LibraryChange.sas”
However, I don’t recommend keeping files in the project folders like that. If you do, then you can’t change them without republishing the project. It’s better to create an external folder on a share accessible to your robots. You can store the path to this folder in a config file, and now you just know the path to your files and can change it in the config file if the folder moves (without republishing).