'Slack command does not trigger App script

I have created a slack app and granted it the needed permissions, then I added a slack command that is connected to a simple google app script that adds info to a google sheet and installed the app on my slack workspace. But when I try to use the command, I always get /register failed with the error "dispatch_failed" and from the logs, I can tell that the request is not reaching the script.

The app script

function doPost(request){
  console.log("GOT here");
  var params = request.parameter;
  var text = params.text; //the options provided after the command as a single string
  //visit https://api.slack.com/slash-commands/#app_command_handling for available payload sent by slack
  var names = text.split(" ");
  var firstName = names[0];
  var lastName = names[1];
  
  addRow(firstName, lastName);//call function to add row as declared below
  
  var response = {    
    "response_type": "ephemeral",
    "text": firstName + " " + lastName +" has been added to our records",
  };
  //finally we return the reponse back to slack
  return ContentService.createTextOutput(JSON.stringify(response)).setMimeType(ContentService.MimeType.JSON);
}

function addRow(firstName, lastName) {
   // more info https://developers.google.com/apps-script/guides/sheets
   var sheet = SpreadsheetApp.getActiveSheet();
   sheet.appendRow([firstName, lastName]);//adds a new row to the sheet
}