How to work with Spotify API via Ruby ( RestClient, Watir...)?

Question

ruby

Hello,
I need to connect via ruby ​​and take a token from spotify (What I did),
but the token that they send me is low-level (from Flow'a client_credentials), and when I change Flow'a, I get a BAD REQUEST.

Token request:

grant = Base64.encode64("#{CLIENT_ID}:#{CLIENT_SECRET}").delete("\n")

respond = RestClient.post('https://accounts.spotify.com/api/token',
                       {'grant_type' => 'client_credentials'},
                       {"Authorization" => "Basic #{grant}"})

token_ext =  respond.split(',')
token_ext2 = token_ext[0].split(':')
only_token = token_ext2[1].delete_prefix('"').delete_suffix('"')
puts 'ACCES TOKEN: %s' % [only_token]

But the problem with the token is not everything, my main task is to work with the playlist.
Firstly, I need to add a new playlist, I tried to do this, but before that I did not work with HTTP Requests in this format.

My attempts to add a playlist (the code below doesn't work):

# respond = RestClient.post('https://api.spotify.com/v1/users/%s/playlists' % [USER_ID],
#                           {"Content-Type" => "application/json"},
#                           {"Authorization" => "Basic #{grant}"})
# respond = RestClient.post('https://api.spotify.com/v1/users/%s/playlists' % [USER_ID],
#
#                           {"Content-Type" => "application/json"},
#                           {"Authorization" => "Basic #{grant}"},
#                           ) { "name" => "New Playlilist" ; "description" => "sdada" ; "public" => "false"}

And so in the end I would like to return to the token, because at the end I was already tired of looking for ruby ​​guides on working with spotify, so I found the "spotify-client" gem. I threw the token into the config and tried to make a new playlist.

config = {
  :access_token => only_token.to_s,  # initialize the client with an access token to perform authenticated calls
  :raise_errors => true,  # choose between returning false or raising a proper exception when API calls fails

  # Connection properties
  :retries       => 1,    # automatically retry a certain number of times before returning
  :read_timeout  => 10,   # set longer read_timeout, default is 10 seconds
  :write_timeout => 10,   # set longer write_timeout, default is 10 seconds
  :persistent    => false # when true, make multiple requests calls using a single persistent connection. Use +close_connection+ method on the client to manually clean up sockets
}
client = Spotify::Client.new(config)
sleep(2)
puts client.create_user_playlist(USER_ID, "ALOHA", is_public = true)

As a result, I got an error that I do not have enough rights, that is, my token does not give me such rights.

Well, the question itself in the end. How can I get the right token (the right token from Flow'a authorization_code) from spotfi through a request using Watir or RestClient ? And also how do I add a new playlist and do such manipulations as adding a track to the playlist, changing the last track with the first one in the playlist and pulling out song data?

Thanks