My Question or Issue
Is there anywhere in the Web API documentation
a mentioning about needing to use a Premium account
in order to send (some of the) Player API requests ?
I have looked in the below sections:
How I've come to this observation
I discovered some requests from the Player API
DO NOT work without an obligatory Spotify Premium plan.
This happened ONLY AFTER I've run a request and got the below response body (excerpt):
Solved! Go to Solution.
You need to be more specific about which requests in particular lead to a 403 where you think they shouldn't.
Many of the API calls the documentation you linked to do in fact state that a premium subscription plan is required.
Like for example under "Start/Resume a User's Playback": If the user making the request is non-premium, a 403 FORBIDDEN response code will be returned.