Soundcloud API authentication always throws "401 - Unauthorized" - authentication

Question

Due to the new updates of the Soundcloud API, I'm trying to update the authentication flow in my code ( the project was using login and password ).
But I'm blocked by a problem, and I'm losing my head.
I follow instructions on this page : https://developers.soundcloud.com/blog/security-updates-api
I manage to get a refresh token and an access token with this :
curl --request POST \
--url https://api.soundcloud.com/oauth2/token \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data client_id=CLIENT_ID \
--data client_secret=CLIENT_SECRET \
--data grant_type=client_credentials
But I'm not able to execute this request, which is an example in the mentionned page, with the access token I got with the previous request :
curl --request GET \
--url 'https://api.soundcloud.com/me/tracks?limit=1' \
--header 'Authorization: OAuth ACCESS_TOKEN'
The request response is always :{"code":401,"message":"","link":"https://developers.soundcloud.com/docs/api/explorer/open-api","status":"401 - Unauthorized","errors":[],"error":null}
I tried with a refresh of my access token, and with the url "https://api.soundcloud.com/me" instead of "https://api.soundcloud.com/me/tracks?limit=1".
And always returning the same error.
Can someone help me ?
Thanks by advance, and thanks for reading.

Answer 1

OK, I think I got it, thanks to this question on github :
https://github.com/soundcloud/api/issues/76
"The client_credentials auth flow is meant only for server-side integration and allows access to public endpoints only. Meaning that for endpoint /me or any other user-related endpoint you have to use the Authorization Code flow which provides the client-side integration."
And here : https://developers.soundcloud.com/docs/api/guide#authentication :
"if your app needs to access only public resources, you can use the OAuth Client Credentials Flow"
I'm done with the error messages too blurry... and with me reading too fast !
I will add the correct authentication method in comments later.
UPDATE : "manual" authentication flow
As the project is behind a VPN, I can't use normal authentication flow ( redirect_uri can't be called by soundcloud !)
So :
Get a "code"
First, authenticate on SoundCloud with the account you want to access ( or ask your customer to do it )
In your browser, type this url :
https://api.soundcloud.com/connect?client_id=YOUR_CLIENT_ID&response_type=code&scope=&state=[random_string]&redirect_uri=YOUR_REDIRECT_URI
Accept the demand and this will redirect you to an URL with the code inside : code=YOUR_CODE. Keep it. If this is done by your customer, simply ask him to copy-paste the url.
That's not really secure, but you can't avoid it if your redirect uri is not accessible from Soundcloud.
Obtain a refresh token and an access token :
With curl, to keep your Client Secret, or App Secret, secret ( indeed :D ). And also the access token.
curl -X POST "https://api.soundcloud.com/oauth2/token"
-H "accept: application/json; charset=utf-8"
-H "Content-Type: application/x-www-form-urlencoded"
-d "grant_type=authorization_code&client_id=YOUR_CLIENT_ID&client_secret=YOUR_CLIENT_SECRET&redirect_uri=YOUR_REDIRECT_URI&code=YOUR_CODE"
This last request will answer in json format. Inside, you'll find an access token, and a refresh token.
Register the refresh token in your projet to reuse it to refresh your access token when needed !