And if the access_token belongs to the user you want to look up, then you don’t have to specify a id or login as the users API will return the user for the authenticating token
res returns an object, that contains the axios response res.data contains the actual body response
You’ll need to JSON decode it (unless axios did this for you)
var data_response = JSON.parse(res.data);
Then you’ll have the actual API response and can grab the users id from that
var user_id = data_response.data.[0].id;
Get Followed Streams needs the users token with the relevant scope attached to it, so call the users API with no query string params, and it’ll return the object that represents the user
That’ll return the user object for the user whom has logged in, then go and call the Get Followed Streams API, something like this, (not tested)