​@bev you can’t!

Manychat will only work with bot <> user conversations in Telegram, it won’t work in channels.

Thanks a million!! how can I blast message to different user conversations with the the bot please?

For that you need to do a broadcast ​@bev 

Here’s how: https://help.manychat.com/hc/en-us/articles/14281228205212-Broadcasting-in-Manychat-Connecting-with-your-audience-at-scale