One of the most downloaded Digi-payments apps in this world is Cash app. But if you unable to download it, then it can primarily be because of simple and plain reason and that is poor internet connectivity. So fix the net connectivity. But if that doesn’t help, then call to Cash App Customer Service.
https://www.customercare-email.com/customer-service/cash-app.html
https://www.customercare-email.com/customer-service/cash-app.html