Once you click on the Pay Now button (in the community you wish to subscribe or the video you wish to pay for, or when your user tries to join your channel), you will be taken to the PayPal payment page.
Check if all the information, along with your invoice is correct and then click on 'Pay Now'. When you click on Pay Now you will be taken to the payment success page, with all your order details in it.
When you click on the 'Return to ________' button, you will be taken to the redirection page.
Here you will be automatically directed to the community, video, or channel that you have subscribed for. Simple, ain't it!