I think its best if you start over and try to follow tutorial as much as possible.
You dont need to use itterable field to connect text and images, itterable field is for some more advanced stuff, and it is not meant to be used here, you are using itterable on some places where you should be using content field in settings tab.
You need to match fields inside of CMS & Builder. So if you are using rich text in CMS, you should connect that field with rich text inside of builder.
If you are using text field inside of CMS, you should connect that with paragraph, span or headings. etc.