1.
Error:Execution failed for task ':app:processDebugManifest'. > Manifest merger failed : Attribute application@allowBackup value=(false) from AndroidManifest.xml:16:9-36 is also present at [com.github.devlight.shadowlayout:library:1.0.2] AndroidManifest.xml:24:9-35 value=(true). Suggestion: add 'tools:replace="android:allowBackup"' to <application> element at AndroidManifest.xml:15:5-47:19 to override.
2.根據建議添加
<application …… tools:replace="android:allowBackup" …… >