In order to receive donations, you will need to set up Stripe (https://stripe.com) payment gateway.
To set up Stripe as a payment gateway, you will need to visit their site at https://stripe.com/ and create an account. Once you have created your account, navigate to your Account Settings and select the API Keys tab. Four API keys will be Displayed. Copy these API keys to the matching fields in the Agape Payment Settings under Billing.