This look similar to this post:- Getting error when Migration user from 6.0 to 6.2 and Could not Install Package from AEM 5.6.1 to AEM 6.3
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The problem here was that your package has all users (at folder level - alphabets, numbers, etc), so what happens is it will replace the existing the folder structure which will remove the existing users including admin and anonymous which are now created with random id.
We resolved this issue by creating user package with individual filters (each user and group path). You can make use of ACS AEM Commons tool - https://adobe-consulting-services.github.io/acs-aem-commons/features/authorizable-packager .html for the same.
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I removed the error causing node and installed the package and it will installed now properly.
~kautuk
Kautuk Sahni