Autotidy is a Spotless feature which learns where your files belong based upon their file extensions. By default Spotless creates an Autotidy task for you, however any task can be configured to learn in this way.
If you configure a task to have a default action of "Ask to create rule" then when Spotless process the files with this task, if there are any unprocessed files or folders you will be prompted to ask what action should be taken for files with each unhandled file extension. Spotless will then automatically create a rule in the task to handle these files in the future. The next time you process files with this file extension using the task, Spotless will already know what action to take and will process them automatically. In this way you can train Spotless where your files belong, and soon they will all be tidied with zero effort.
When using the "Ask to create rule" the task is first used to process the files, and Spotless will only prompt you to choose an action for file extensions of any files that are not handled by the rules. This allows you to customise the Autotidy task to handle files using more complex rules and you will only be prompted if the files are not handled.
On first installation the Drag & Drop feature is configured to run the Autotidy task, allowing Spotless to quickly learn where your files belong, however you can also setup Automation to run the Autotidy task on any folder at specific times / days.