You can retrieve your Client ID & Secret Key through DOKU Back Office by simply go to Business Account > Service.
Save your payment credential
You can save it in your device or anywhere you think is safe. Also, you can visit this page later if you need to see your payment credential.
Please keep your Client ID and Secret Key confidential, especially your Production Client ID and Secret Key. It is your payment credential to accept payments.
You now can start integrating with DOKU. You can choose which integration type that suits your business needs.