How to receive webhooks from a public channel?

I successfully created a bot, that receives webhooks, if I chat with the bot directly. 

I also want to receive webhooks and handle webhooks from other channels. For example a public channel.

- I added the boot as an Admin to the channel. 
- Set allow message from unknown chats to true and added the chat id to the database.
- I set the privacy to disabled.

Did I miss something?