Paypal api – Accessing PayPal Commerce Platform API

I’ve created a new sandbox app in paypal and checked all controls under settings.

I’m manually making a request to get an access token using cURL as suggested in the docs.

Then I make a POST request to /v2/customer/partner-referrals. I’m simply copy-pasting the request from the docs from here.

The response I get is:

HTTP/1.1 403 Forbidden
... 
{
    "name":"NOT_AUTHORIZED",
    "message":"Authorization failed due to insufficient permissions.",
    "debug_id":"...",
    "information_link":"",
    "details":[{
        "issue":"MISSING_SCOPES",
        "description":"User doesn't have this API in their scope"
    }],
    "links":[]
}

The partner onboarding page says, that I get 401 Unauthorized if the account doesn’t have permissions to access the commerce API. But at the same time I can’t find a way to request certain APIs to be included in the scope.

How can I authorize a request to PayPal Commerce API ?

UPD

There’s an additional question which may actually be a reason for my issue. Am I required to apply and be approved for the Parter Program before I can use sandbox APIs ?
There’s a flow chart on the paypal website for PayPal Commerce Platform integration. It clearly shows that develop the app while using sandbox while I wait for the app approval. How show I interpret this image then?

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