Symfony developers can now integrate Neo4j with their applications using the neo4j-bundle. To set up multiple connections, they need to download and install Neo4j Desktop and configure the Symfony application to connect to both local and remote instances. The bundle provides a secure way to manage credentials in a .env file, and Symfony's built-in commands allow developers to inspect and interact with their configuration. A custom controller can be created to test connections and verify that they are working correctly. This setup gives developers the flexibility and scalability their applications need.