“Compatibility: Ink & Slide are designed to work with iPad 4, iPad mini (all models), and iPad Air (1st generation).
Note: There is a known, intermittent issue with the iPad Air 2, in which Ink stops drawing mid-stroke. This will require Adobe SDK (software) updates to resolve. Not fully compatible with iPad Pro”
This is from Amazon. Regardless of Astropad compatibility it’s not fully compatible with iPad Pro. Hope that helps.