What payment systems are already contracted? What payment systems you will expect to work?
As much as I could see from Whitepaper I found this information:
Now we are negotiating with QIWI, OkPay, AdvancedCash. Further action is to negotiate with PayPal, Skrill. And then we are going to negotiate with VISA and MasterCard.
End also I found that in 2019 Streamity planning to:
Creation of own payment system and integration with STREAMDESK service