This will guide you through the one-time process of installing the Keyboard Extension for this app:
From your home screen, go to Settings
Tap Add New Keyboard...
In the Third-Party keyboards list, find and tap on Adult Emoji 💋
Back in Keyboards, tap Adult Emoji 💋 again
Turn on the switch for Allow Full Access
Tap Allow (please also read below)
Important Privacy Note
When you Allow Full Access, an alert pops up. This alert is well known to be intimidating, but is irrelevant to this keyboard extension because you don't use it for typing, just for emoji. Your privacy is 100% safe.