Is it possible to create a Spreadsheet in a specified Folder or do I have to use the Drive API to move it afterwards?
Depends on how you want to use and how do you create your Spreadsheet, it is possible to create Spreadsheet like so.
function create_ss_in_folder(folder, name) {
var ss = SpreadsheetApp.create(name);
var id = ss.getId();
var file = DriveApp.getFileById(id);
var folder = get_folder_by_name(folder);
folder.addFile(file);
DriveApp.getRootFolder().removeFile(file);
return id;
}
Again with not much info i do not know why would you create Spreadsheets manually when there is programmatic way to do it.
Some helpful links:
https://developers.google.com/apps-script/reference/drive/folder
https://developers.google.com/apps-script/advanced/drive
Update:
//Move it to desired folder
var fileID = 'Your file ID'
var folderID = 'Folder ID'
var file = DriveApp.getFileById(fileID).getName()
var folder = DriveApp.getFolderById(folderID)
var newFile = file.makeCopy(file, folder)
// This will remove it from root.
DriveApp.getFileById(fileID).setTrashed(true)