There will be no CREATE button in the Preview (and also not in a deployed app) unless you activate the draft handling in your business object. These steps ("use draft" in projection behavior definition, "with draft", total etag and draft actions in data view behavior definition, create draft table...) are missing in the tutorial. I spent half a day investigating but no regrets - I learnt so much!
Tutorials: https://developers.sap.com/tutorials/abap-environment-behavior.html
There will be no CREATE button in the Preview (and also not in a deployed app) unless you activate the draft handling in your business object. These steps ("use draft" in projection behavior definition, "with draft", total etag and draft actions in data view behavior definition, create draft table...) are missing in the tutorial. I spent half a day investigating but no regrets - I learnt so much!