A trigger folder is simply a Windows folder that Easy2Sync watches for changes. if any file is changed by any application, a sync can be started.
A trigger file is a file which existence is enough to let Easy2Sync start the synchronization of a certain task. The contents of the file do not matter. As soon as Easy2Sync finds the file, it will be deleted.
You can use this to start a synchronization when another computer is started. For this create a text file with the name "Trigger.bat" and write the following text into it: "@echo "test" >FILENAME". You may choose any file for this, as long as you also enter the filename on this computer into Easy2Sync. If there are spaces in the path, you must enclose path and filename in quotation marks. Now simply create a shortcut to the file in the startup folder.