As with any module, this is also disabled by default.
Once enabled, by default a large number of revisions (99 to be specific) will be set to be on the safe side.
Changing this to say 5 will ensure that only the last or most recent 5 revisions will remain in the database and the rest automatically purged. This number is per post i.e., typically per Page and per Template.
For the revisions purging to happen for existing Pages and Templates, they need to be saved/updated either in the WP editor or in the Oxygen editor. Updating a Page/Template in the WP editor will not immediately reflect the updated number of revisions but can be seen after a page reload.
With new Pages/Templates created after enabling the module, revisions purging will be automatic per the set number.