This article is complementary to the book, Hands-on Data Virtualization with Polybase, which you can find here and which contains additional information and tips to test Polybase for free, or at least at the lowest cost.
One of the most impressive features of PolyBase in SQL Server 2019 is the ability to create scale-out groups, pairing it with its predecessors, Parallel Data Warehouse (PDW) and Analytics Platform System (APS). In order to test this feature, you can create a free Azure account that gives you $200 credits for 30 days and allows you to use up to 4 CPUs overall;