Google Sheets Data Validation with List Dependencies

Is this even possible with Google Sheets? I've looked around and found some explanations on how to accomplish this by using scripts. However, the issue remains because I'm unable to have my script recognize my sheet. Something with not able to recognize "SpreadSheetApp" within my code.

I basically have a table I'm attempting to reference using a dependant dropdown or rather a data validation list.

Once the Sales Rep is chosen from the first Data Validation cell then that configures the states that are for that sales rep in another data validation cell adjacent.

Here is an image of my table for the sales reps which are on another sheet.

Any help would be very appreciated.

btw here's the script I can't seem to get to work at all.

function myFunction() { 
  var ws = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Data"); 
  var list = ["a","b","c"]; 

  var rule = SpreadsheetApp.newDataValidation().requireValueInList(list).build(); 
  ws.getRange("C2").setDataValidation(rule);
}