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