I would like to share with you a code snipped of how to access subcollections in the Cloud Firestore database.

Lets say we have this structure:
- Users
     |
 -- Tasks

Our exercise is to access the tasks list of a certain user.

import { compose } from "redux";
import { connect } from "react-redux";
import { firestoreConnect } from "react-redux-firebase";

...

const enhance = compose(
  firestoreConnect(props => {
    return [{ collection: "users", doc: props.uid, subcollections: [{ collection: "tasks" }], storeAs: `${props.uid}-tasks` }];
  }),
  connect(({ firestore }, props) => {
    return {
      tasks: firestore.ordered[`${props.uid}-tasks`] || []
    };
  })
);

...

const Tasks = ({ firestore, tasks }) => {
    return <YOUR_TASKS_LIST_UI>
}

export default enchance(Tasks)

It's really that simple!
Happy coding! 👨‍💻