If you see a loading spinner in run mode then please try to run the application once again after updating your project's Firestore rules.
Here are the steps to update Firestore rules:
Go to Firestore and then select Settings.
Copy the Firestore rules by selecting the copy icon.
Next, go to Firebase console and open you application.
Select Firestore Database and then select the Rules tab.
Paste the copied rules(from FlutterFlow) there.
Now return to FlutterFlow and re-run your project
