When executing 

npm run android

I got an error saying:

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

to fix this on Windows, you need to go to the Android SDK folder. Once there execute:

C:\Program Files (x86)\Android\android-sdk\cmdline-tools\7.0\bin> .\sdkmanager.bat --licenses

After this, accept all the new Google surrender terms

Accept all the licenses and then execute again.