Sending data to a specific cell in google sheets

I have tested your script and it works OK for me.

function doPost(e) {
  var ss = SpreadsheetApp.openById('<SheetID here>');
  var sh = ss.getSheetByName('Sheet1');
  var params = e.parameter;
  
  var row = parseInt(params.row);
  var col = parseInt(params.col);
  var val = params.value;

  sh.getRange(row,col).setValue(val);

  return ContentService.createTextOutput("value set");
  
}