Traditional retailers, such as AGL or Origin, are a fixed rate or a time-of-use plan. Choose the retailer on the grid feed and select the plan.
Wholesale retailers, such as Amber and Local Volts, need the credentials that retailer gave you. After they are saved, use Fetch energy prices to load the current buy and sell rates.
Gridkeeper is the control layer. It is not the retailer, and it does not replace the plan you already have.