Facebook messenger - add extension to composer drawer

[maxutolen]

I'm new in creating bots and extensions in Facebook. I need your help, any help will appreciate.
My problem is, when user clicking "+" button in composer drawer, there is not appearing my extension when parameter in_test: true. What did I do to fix this problem.

1. Configured whitelisted_domains domain (domain has 'https', also website uploaded in herokuapp.com). Result was success
2. I've created a simple page (just to test the concept) and tried to make this the home_url as described here https://developers.facebook.com/docs/messenger-platform/reference/messenger-profile-api/home-url#post. Result was success
3. Created new Facebook page and attached it with bot (application in developer console).
4. Also configured bot in public mode.
5. Added tester user in "Roles" page in the console of the application.
6. I tried to delete "Messenger" application from android phone, also to update.

I'm using PHP with this library https://github.com/pimax/fb-messenger-php
Am I missing something here? What's the correct technique for making this appear?
Help please, if there's simple example just for showing extension dialog window, comment please.

Many thanks

[wittfabian]

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