As expected, this has a lot of bugs. The images are a little over exposed often. It will crash with default settings and when it crashes you would need to restart the phone to make it work again ( default camera fails to open as well ). I spend a few hours trying different settings and found the Night Sight, Portrait mode and HDR+ working with the following settings. ( I am on Android 8.1 btw ). It doesn't work on EMUI 9.
Go to More -> Settings -> Advanced -> Fixes and change the 'Viewfinder Format' to PRIVATE.
What doesn't work : Front Camera, Slow Mo.
If you want to add Saturation go to HDR+ settings in the menu and increase Highlights and Shadows Saturation to your liking.