“Failed to install the following Android SDK packages as some licences have not been accepted” error

You need to accept the licences before building.

According to Android SDK docs you can use the following command depending on the sdkmanager location: Docs on --licenses option seems to be missing though.

yes | sdkmanager --licenses

GNU/Linux Distributions:

yes | ~/Android/Sdk/tools/bin/sdkmanager --licenses

macOS:

export JAVA_HOME=/Applications/Android\ Studio.app/Contents/jre/jdk/Contents/Home
yes | ~/Library/Android/sdk/tools/bin/sdkmanager --licenses

Windows:

%ANDROID_HOME%/tools/bin/sdkmanager --licenses

Flutter:

> flutter doctor --android-licenses