Last year Linode announced a new Linode Manager that you can access on cloud.linode.com, it has a completely different interface from the old Linode Manager. However, it also uses the latest version of their API. All tokens generated from the new manager can only be used with their new API.
Starting today, Forge is using Linode's latest API version. While customers can still manage servers added through the old API, new servers can not be created unless a new Linode provider is added by providing a valid APIv4 token.
To create a new provider, head to your profile settings under the "Server Providers" tab. Select "Linode Cloud" from the list, and provide a valid token:
Make sure the token is generated on cloud.linode.com not manager.linode.com.
If you don’t have a Forge account, now is a great time to sign up. Forge allows you to painlessly create and manage PHP 7.3 servers which include MySQL, Redis, Memcached, and everything else you need to run robust, modern Laravel applications.