The button Save Draft is not clickable so it does not allow to create a new guide. "The slug must be unique" error is showing.
A slug is the part of a URL that identifies a particular page on a website in an easy-to-read form.
If the error "The slug must be unique." shows this means that there's an existing Guide with the same title so it cannot be used again. This prevents from creating duplicates and confusion.
In this case, use a different title or make some small changes in the naming.
The button "Save Draft" will then be clickable.