I was able to get authenticated, I had to read through your const.py to see which headers were needed, then put it in the json format from ytmusicapi link. Copying the whole thing didnāt work.
I am not able to load any playlists, I tried private, unlisted and public but it just shows āloadingā
{
"Cookie": "",
"Accept-Encoding": "gzip, deflate, br",
"Accept-Language": "en-US,en;q=0.5",
"Authorization": "",
"Host": "music.youtube.com",
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0",
"X-Goog-AuthUser": "null",
"X-Goog-Visitor-Id": "",
"x-origin": "https://music.youtube.com",
"X-YouTube-Client-Name": "",
"X-YouTube-Identity-Token": "",
"X-YouTube-Page-CL": ""
}