Go to https://www.unifonic.com/ and register an account.
Complete the required field in the plugin general settings.
To recover the REST API key, please follow the steps below:
1- Navigate to https://communication.cloud.unifonic.com/sendername
2- Click on “Add new sender name” and create a Sender Name
4- Choose app name and sender name and add a description
5- Click on Save
6- Copy the key into the plugin panel (see image below)