I replied to you in another message you posted. Perhaps you didn't see my reply.
There is a great deal of confusion about the meaning of saving a document "online". I have never seen a setting option to save an InDesign file online in any version. Can you tell us exactly what the message actually said.
It's possible to create a Creative Cloud File by saving in the Crative Cloud Folder that is created on your computer but this is to allow you use it as a backup or a way of sharing files. In no way is there any way to set it up so this happens instead of being saved to your computer as a primary way of saving files.
In the future, it will be possible to save InDesign Cloud files (which can now be done in Illustrator or Photoshop). But this feature is still in beta testing so it's not something you could get access without using a special version of InDesign.