This site names this specific bonus guide directly: an intimacy-themed digital guide advertised with select packages, worth understanding alongside this site's own choice not to show cover art for it.
This site describes it only briefly, as an intimacy-themed digital guide — it is direct that it has not reviewed the guide's contents itself, and given the subject matter, has not displayed cover art for it.
Choosing not to display cover art for adult-themed material, while still disclosing that it exists, is a more restrained approach than some competitor sites in similar bonus-content categories take.