Issue with Move to iOS android app to migrate to iphone
I think you found a solution in meanwhile.
Anyway I faced the some problem yesterday and I even contact Apple to get some information. They said me that the version installed in my new brand iPhone XS is now accepting just 6 digits instead the 10 Android was requesting me. And proposed me to use another app called MCBackup which is a contact transfer and save app for android and iOS.

Then I start to think a bit. First I tried the current version of Move to iOS which didn't run on my android. So I started to look into a older version what I got this morning. The one I found was from 2018 called Move to iOS 2.10.0 (com.apple.movetoios_2.10.0-2100_minAPI14(armeabi)(nodpi) and it can be downloaded at https://www.apkmirror.com/apk/apple-inc/move-to-ios/move-to-ios-2-10-0-release/#downloads.

Please assure that this is the version, older ones (1.57 and 1.59) do not work, I tried.

I hope I could help some other who intent to migrate all Android's data to the new iPhone...