Just clear the Lockrz data and cache in your phone settings. (https://www.howtogeek.com/355154/how-to-clear-app-data-and-cache-on-android-to-solve-common-problems/)
It seems that something that is being auto-restored when the app is installed which is incompatible with some phones. To date, the only users reporting this are Pixel 4 users which makes me think that maybe the lack of a fingerprint reader is causing issues if your previous device had one.
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