I'm from the Adwords API Team, i'd be happy to assist you in retrieving a developer token so you can advance to making you first API call. You'll only be able to sign up for API access from your production AdWords Manager account. You need to create a Production AdWords Manager account by following the instructions provided here and apply for API access from your production manager account by following this guide. Please note that you'll be granted a developer token with test access which can be used to target test accounts. You need to submit the basic access application form to get your developer token approved. After token approval, you'll be able to target production accounts as well.