You'll need some records in the org to get started. If you have an aggregator account with a supported aggregator,use that to import some providers and services. If you don't, you can create some manually as described below.
In setup, under custom metadata, go to the RefRecSettings and Manage Records
Set your default latitude/longitude (unless your office is in the Salesforce Tower in San Francisco), max distance, and email address
If you need to use a tool to find lat & long coordinates for your default address, this website is useful: https://www.latlong.net/
Create one or more accounts that will represent a provider
In the refrec__Service__c object, add one or more Services that the Provider provides and fill out all the information. Be sure to populate its location fields (lat/long) with values close to where you sample contact is located On the related tab, also add its operating hours.
Create a contact to represent someone you want to create a referral for. Their geolocation (uses the Other Address field by default) and age needs to match the service to be able to see it.