LINE Login API – Error 403: Permissions Issue

Question

I am trying to add LINE login to my app. When I try to call the LINE auth URL, I get the following error:

Error 403: You do not have permission to use the API. Please check the permissions granted to your plan and account.

I have successfully configured my Developer account on the LINE console, a provider and a channel. I cannot find any information online, nor can I find any helpful settings under my LINE account or Developer Console account. The prerequisites on their docs don't seem to mention anything either.

Does someone know a workaround for this?