Building with "Google VR Transition 2D"

I cannot build for Android with the “Google VR Transition 2D” plugin enabled. I can build with the Google VR plugin and it works just fine. I would like to use the VR-2D transition node from the “Google VR Transition 2D” plugin, but even an empty project is unable to build with transition plugin enabled.

The console says the following:

Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :common_library:processDebugManifest
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :permission_library:mergeDebugNativeLibs
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :app:processDebugManifest FAILED
Packaging (Android (Multi:ASTC,DXT,ETC2)): Z:\app\src\main\AndroidManifest.xml Error:
Packaging (Android (Multi:ASTC,DXT,ETC2)): uses-sdk:minSdkVersion 21 cannot be smaller than version 24 declared in library [:transition_library] Z:\transition_library\build\intermediates\library_manifest\debug\AndroidManifest.xml as the library might be using APIs not available in 21
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): See http://g.co/androidstudio/manifest-merger for more information about the manifest merger.
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :transition_library:mergeDebugNativeLibs
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :downloader_library:bundleLibResDebug
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :common_library:javaPreCompileDebug
Packaging (Android (Multi:ASTC,DXT,ETC2)): Suggestion: use a compatible library with a minSdk of at most 21,
Packaging (Android (Multi:ASTC,DXT,ETC2)): or increase this project’s minSdk version to at least 24,
Packaging (Android (Multi:ASTC,DXT,ETC2)): or use tools:overrideLibrary=“com.google.vr.sdk.samples.transition” to force usage (may lead to runtime failures)
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :common_library:generateDebugRFile
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :app:mergeExtDexDebug
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :transition_library:parseDebugLibraryResources
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :common_library:mergeDebugNativeLibs
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :downloader_library:bundleLibRuntimeDebug
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :downloader_library:mergeDebugNativeLibs
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Task :permission_library:parseDebugLibraryResources
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): FAILURE: Build failed with an exception.
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): * What went wrong:
Packaging (Android (Multi:ASTC,DXT,ETC2)): Execution failed for task ‘:app:processDebugManifest’.
Packaging (Android (Multi:ASTC,DXT,ETC2)): > Manifest merger failed : uses-sdk:minSdkVersion 21 cannot be smaller than version 24 declared in library [:transition_library] Z:\transition_library\build\intermediates\library_manifest\debug\AndroidManifest.xml as the library might be using APIs not available in 21
Packaging (Android (Multi:ASTC,DXT,ETC2)): Suggestion: use a compatible library with a minSdk of at most 21,
Packaging (Android (Multi:ASTC,DXT,ETC2)): or increase this project’s minSdk version to at least 24,
Packaging (Android (Multi:ASTC,DXT,ETC2)): or use tools:overrideLibrary=“com.google.vr.sdk.samples.transition” to force usage (may lead to runtime failures)
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): * Try:
Packaging (Android (Multi:ASTC,DXT,ETC2)): Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): * Get more help at https://help.gradle.org
Packaging (Android (Multi:ASTC,DXT,ETC2)):
Packaging (Android (Multi:ASTC,DXT,ETC2)): BUILD FAILED in 18s
Packaging (Android (Multi:ASTC,DXT,ETC2)): 69 actionable tasks: 69 executed
Packaging (Android (Multi:ASTC,DXT,ETC2)): ERROR: cmd.exe failed with args /c “D:\BoringStuff\LRZBridgeofKnowlegde\bridgevr\Intermediate\Android\armv7\gradle\rungradle.bat” :app:assembleDebug
Packaging (Android (Multi:ASTC,DXT,ETC2)): Took 40.6194438s to run UnrealBuildTool.exe, ExitCode=6
Packaging (Android (Multi:ASTC,DXT,ETC2)): UnrealBuildTool failed. See log for more details. (C:\Users\alexk\AppData\Roaming\Unreal Engine\AutomationTool\Logs\F+Games+Epic+Games+UE_4.25\UBT-bridgevr-Android-Development.txt)
Packaging (Android (Multi:ASTC,DXT,ETC2)): AutomationTool exiting with ExitCode=6 (6)
Packaging (Android (Multi:ASTC,DXT,ETC2)): BUILD FAILED
PackagingResults: Error: cmd.exe failed with args /c “D:\BoringStuff\Intermediate\Android\armv7\gradle\rungradle.bat” :app:assembleDebug
PackagingResults: Error: Unknown Error

Does anyone know how to make the VR-2D transition work?