In Chats mode, click on a rich menu from the Rich Menu pane located on the bottom right to activate it.
I made a template message in Bot Designer but the link doesn't work.
Check if you have included "http://" or "https://" in the URL. The link must be in the same URL format as used on browsers.
Message actions will work normally when added to the chat in Chats mode.
The actual LINE chatbot only accepts URLs starting with "https://" to ensure security. LINE Bot Designer doesn't have this limitation to encourage the creation of any chatbot prototype.