I understand the problem you are facing is the account created from LINE Manager don't appear in the LINE Developer site for configuration. Am I correct?
If yes, The Account created from LINE Manager Site is not originally have Messaging API enabled (Not originally Link to LINE Developer site). So if you want to enable it, You have to do these following steps
- Head to the LINE Manager site and go to Settings page of the account you want to link.
- Click on the Messaging API Tab on the left ( Direct URL:
- Click Enable Messaging API
- Select the sutiable provider for this channel. (The provider list are related to the one you created or you have permission to access to it in the LINE Developer Site)
After you've done this. The account will now appear in the LINE Developer site :)