Only once you have purchased a Journey in full, will you have the option to rate it and write a review.
Once you have purchased a Journey it will show up in your Library under “My Journeys” as shown below…
Simply tap on the Journey, then tap on the content bit to begin working through it. To view a list of all the Journey content or to rate and write a review, tap on the “Menu” icon as shown below…
Then tap “Write Review“…