Error message : Failed to install the following Android SDK packages as some licenses have not been accepted.
This is kine of normal issue for early stage development of mobile app using React-Native. Follow the step below to resolve this issue by accepted all the required licenses.
For windows users :
On your command prompt (CMD), point the directrory to your SDK folder
next insert this command
you need to enter letter ‘Y’ to accept all the required licenses.
After all required licenses has been accepted, rebuild your app.
Other Reference : stackoverflow.com