Guys, I found the solution. Is quite simple and tested only on iOS for now.
Here's my reference: https://github.com/FlutterFlow/flutterflow-issues/issues/2162

I'll make it in steps to simple:

You'll need to upload your code to Github repo (go to developer menu at the top > Push to repository)
When it's done, go to github repository > find Pubspec.yaml > edit the version number of your app (version: 1.0.0+9 for example).
Then go to folder IOS > Runner and edit the file info.plist
1. Find these lines:
  <key>FacebookAppID</key>
  <string>YOUR-FACEBOOK-ID (usually a lot of numbers)</string>
Then bellow insert theses lines:
<key>FacebookClientToken</key>
<string>YOUR FACEBOOK CLIENT TOKEN</string>
You can find the facebook client token on this url: https://developers.facebook.com/
1. Select your app in facebook
2. Go to App Config (or something) > Advanced.
3. In Security Box i'll find a client token
Update the info.plist commiting git to flutterflow branch.
Then go back to Flutterflow > Mobile development > and select Deployment source and check github repo
Insert flutterflow branch name (usually \"flutterflow\")
Deploy to App Store

You can do the same for Android, but it is inside AndroidMainfest.xml - you got it.

PS: Every time you commit from flutterflow to github, you'll have to do these steps again, so save this piece of code above.

Hope it helps you!

The app crashes immediately in Testflight