RevenueCat issue

I’ve done the RevenueCat tutorial but when I test-run my app on real device, it keeps crashing.
I made my app pop up a paywall if the user is not subscribing my app. however when I launch my app there’s a black screen and the last line of the debug console is ‘No Initial App User ID’. Does it mean there’s a problem with generating app user Id?
And there’s a thread appears on ‘extenstion AnyDecodable’ which I have no Idea what it means…
Did I forget something? Can someone help me with this issue?