Player.IO only provides the actions, tracking and payment systems, but it is always up to you game developers to find and connect with partners and negotiate the actual deal.
In the PartnerPay admin panel there is a tab for viewing partners. On this page you can find information about all the partners that are available through Player.IO, such as which web pages they have, and a contact email where you can reach them.
Similarly, partners can view games on Player.IO that have defined PartnerPay actions, and can contact the developers of those games. This means that when you set up your PartnerPay actions, you should fill out the extra information about your game and provide a URL where partners can test the game, in order to successfully market your game to the partners.
Partners can also see all the non-exclusive actions you've set up in your game, and this is another great way for you to advertise what your game offers.
When talking to a partner, you are free to negotiate an individual deal for that partner.
When you set up actions in the admin panel, you have the option of making each action exclusive to a specific partner. If a partner can offer you something extra, you can use this system to increase the commission of a general action, or you can make actions that are only available to that partner.