Business Directory Plugin – Google Wallet

Hi, I am setting up Business Directory Plugin: https://businessdirectoryplugin.com/

It features “Google Wallet” in the payments section, and I would like to use this for free to avoid having to buy the paypal module for $69. I have set up my Google Wallets Account, now the plugin is asking for: “Seller Identifier” and “Seller Secret” WHERE DO I FIND THIS DATA?

It also says “For recurring payments to work you need to specify a postback URL in your Google Wallet settings.
Please use https://usd…………… as the postback URL.” WHERE/HOW DO I INPUT THIS DATA?

Thanks!