Add the bot as Channel admin
1. Enter in the "channel conversation" and tap on the name at the top.
Then tap on the "Info" icon (or "Gear" icon, it depends on the devices and OS)
2. Now select the "Administrators" label and then "Add Administrator".
Then search the name of the Bot you have previously created.
3. Now you have to choose the permissions to give to the new administrator and then you've done!