What are you trying to do with the token? If you simply want to retrieve a user’s access/id tokens, there are easier ways than working through the entire code flow. For instance, you can set up a password grant and exchange username/password directly for tokens, or you could use our authentication API debugger to get them programmatically.
Take a look at this thread that covers the topics I just mentioned.
If you want to do something different, let me know and we can work through it.