Where and why we are using firestore indexes?
If you want to set up the Business Directory App, you also have to deploy the advancedSearch cloud function. For this function to work as it should you have to setup also the indexes in firestore.
NOTE: The advancedSearch cloud function is not working in React App Builder - SaaS.
Deploying the indexes
All you have to do is to open the functions folder in your terminal, which is located in cloud-functions-for-rab -> functions, then run the command below.
firebase deploy --only firestore:indexes