Here is the step-by-step guide in English for the Test/Sandbox environment based on the provided images:

Projects -> Project settings -> Payments -> Unlimit

Callback secret-
Unlimit dashboard -> settings -> wallets -> [CLICK YOUR WALLET ID] -> Show credentials -> Callback secret field

Terminal password
Unlimit dashboard -> settings -> wallets -> [CLICK YOUR WALLET ID] -> Show credentials -> Terminal password field

Terminal code
Unlimit dashboard -> settings -> wallets -> Terminal code