Unfortunately stacked series aren't in the Android version yet.
We released V1.0 of the product with a minimum core feature set (less than the iOS Standard version) for fairly simple charts with limited customisability, which suffice for a reasonable proportion of our customers. We're adding features incrementally to bring it up the level of the iOS version (Standard first, then Premium) over a number of fairly frequent (monthly) releases, with version V1.1 now out. V1.1 added bar charts, legends, and axis styling. V1.2 will follow with Selection and Crosshairs, provisionally scheduled for mid-November.
The prioritisation in our roadmap beyond the forthcoming release is flexible and driven by customer demand, so please let me know if there are any other features you require for your app. Obviously I can't promise anything, as we have many customers with different priorities and we do intend to complete the Standard version before embarking on Premium features, but it's possible that we may be able to let you have some of what you need sooner rather than later.