On Telegram, click on "New Channel".
Fill your channel info.
Set the channel as public and choose a unique name for it.
Once created, click on "info".
Click on "Administrators".
Click on "Add Admin"
Find the bot you previously created and add it as Admin.
Set the right permissions.
Next, open your Bulletin account, go to "Messaging Profiles", click on "+ Add messaging profile" and on "Telegram Channel".
Get back to Telegram to get your Channel share link which will look like "https://t.me/thedigitalnews" and paste it on the input box named "Channel Link".
If you plan to use this channel for testing purposes, click on "Is Test". Finally click on "add channel".