Error: The prefix “tools” for attribute “tools:overrideLibrary” associated with an element type “uses-sdk” is not bound
May Manifest is not merged due to above error and you also found this error in unity
Unable to merge manifests
This problem is usually caused by some plugin in your project.
How to Fix this ?
Find All AndroidManifest.xml from the plugin in your project, open it and then add xmlns:tools="http://schemas.android.com/tools" under <manifest xmlns:android="http://schemas.android.com/apk/res/android".
It looks like this