Currently, Paypal is unable to be integrated with our system in a way which would give a viewer the complete Concert Window experience with minimal data entry and complete security. Using Stripe on the viewer's end means that viewers are able to tip the artists multiple times right when watching the show and in complete safety without exiting the show itself.
We will be working on implementing PayPal payments in the future, but for the time being, it is not an available feature.
Wondering what Stripe is, or if your card information is secure? Check out this article.