Hi Enrique,
Thank you for reaching out to us. Unfortunately developer token, client id, customer id, and client secret are all necessary to call AdWords API. You can find how to obtain the client id and client secret using these steps. Your developer token and customer id should be visible in the Google Ads UI. Sign into your Manager account and your developer token should be visible under “Tools and Settings” > “Setup” > “API Center”. Your customer Ids should be visible under “Accounts” when you log into your manager account. If you’re trying to query for other user’s customer ids not under your manager account, this is not possible with the API. Please let me know if you have further questions.
Thank you,
Bryan, Google Ads API Team