403 Forbidden error when trying to add song to another collaborative playlist with Spotify Web Api

Question

Here is the code I am using to add songs with a button I made. The button works fine, as I am able to add songs to my own playlists. However when trying to add songs to someone else's collaborative playlist, I get a 403 forbidden error.

I have followed the playlists to which I am trying to add songs .I have been able to add songs to that playlist with the desktop app however it is not working on my web page. I don't know if its an error in the code or if the API doesn't allow for collaborative playlists to have songs added to them. My scopes for this project are playlist-read-private,playlist-modify-private,playlist-read-collaborative user-library-modify,user-read-private user-read-email. So I don't think they are an issue either.

document.getElementById('button1').addEventListener('click', function() {
    var myid=localStorage.getItem('SpotId')
    var playid=localStorage.getItem('URI')
    var trackuris = document.getElementById("selections").value;
    console.log(trackuris)
    var uris=[trackuris];           //create an array with the trackuri stored within
    //adding track to playlist using myid, playid, and uris to fill function
    spotifyApi.addTracksToPlaylist(myid,playid,uris).then(function(data) {
        console.log('Added', data); //logging data returend from spotify to console
        document.getElementById('list').src = document.getElementById('list').src;
        var select = document.getElementById("selections");
        $('#selections').empty();   //deletes previos entries upon adding song to playlist
    });
});

Answer 1

This is a limitation of the API. Only playlist owners are able to modify collaborative playlists through the API.