The information required to populate the Adyen card processor dialog can be found on your Adyen account.
Sites > Edit Site > Payment Tab
Display Name: String used for display when referring to the device
Merchant Account: Find on Adyen site. Settings > Merchant accounts
Environment:
Test for a Test Adyen account
Live for a Live Adyen account
API Key: Find on Adyen site. Developers > API credentials > pos_ws > Generate API key
Payment API Url and Checkout API Url: Find on Adyen site. Developers > API URLs