This has been brought up before by others, however Pega Robotics is not designed for testing. There is no notion of validation of expected values and it provides very little diagnostic and debugging capabilities from a testing perspective. Its express purpose is to automate repetitive tasks in legacy software.
Selenium based test frameworks have deep support across all manner of web based software and is by far the most popular UI testing solution out there for browser based testing. There are many forums for support, customized and advanced frameworks and is widely adopted by partners, customers for Pega, including Pega ourselves to do end to end UI automation.
There is a selenium starter kit that is available for Pega applications on the marketplace. It has a getting started guide on how to run and extend the framework for your application and it also supplies examples tests for the CRM based applications from Pega.
If you are interested in a more in depth tutorial or on boarding with Pega, there are Pega partners who specialize in testing such as Valori whom you can reach out to.