you want to use records array as a collection data, collection will iterate on it and provide each item to the children which are your individual items
With CMS.data.data.records[0].fields["Single Line Text"] I get "one. one, one" and with CMS.data.records (In the tutorial they say to stop before the 0, I get this
I would recommend watching tutorials and doing it after the tutorial exactly as they show it, so you first get something working and understand how it works before you jump into more advanced use cases that do something different