Requirements: administrator role.
- Go into Channels.
- On the channel’s card (WhatsApp, Telegram or Web), find the “Allow attachments” row.
- Turn the switch on. The change is saved instantly and applies only to that channel — you can have attachments enabled on the web chat and off on WhatsApp.
Result: the channel starts accepting incoming files; on the web chat, the visitor also sees a paperclip to attach one.