What I'm getting from your post, is that you're having problems connecting from the iPad's SlingPlayer Mobile app.
In this case and before we provide any response, please provide information about error messages, network layout, etc. That way you can receive a proper response from the forum users.
Besides that, you can skip the message asking you to purchase the app. once you do that you will be able to download the application without a problem since you paid for it already.
I also have an ipad with ios5 and when I go to the app in itunes, I get the message action requested could not be completed. Is the application available for all itunes stores? I'm not in the US itunes store and I dont know if that is the problem.
Best regards and thanks for your prompt answer