You’re pretty late to Astropad.
The Astropad team is eliminating ALL third party, smart Bluetooth stylus support by the end of 2018.
So, this app is NOT going to be possible to use with any other iPad other than iPad Pro or the new 2018, 6th gen 9.7 inch screen iPad.
So Astropad will be useless on any other older iPads, by the end of year, and will suck for any older iPad users.
No palm rejection or pressure sensing with third party Bluetooth smart stylii on older iPads by year’s end.
Also, Astropad needs a Mac with an OS of OS X 10.10 or higher, now.
Gone for the Standard version is a minimum of Mac OS X 10.9.5.
Plus, the Standard version of Astropad needs iOS 11, now, too!
So, Astropad will be completely useless to older iPad/older Mac OS users.
For a stylus for older iPad models, you might get away with either a fine point, battery powered, so-called “active” capacitive stylus or a disc end type capacitive stylii.
Most other popular drawing apps still support third party, smart, Bluetooth stylii.
For your iPad model I strongly and honestly recommend the Adonit Pixel.
Purchase the Adonit Pixel, DIRECTLY, from the Adonit website to ensure that their Bluetooth stylus has the latest hardware firmware.
These Bluetooth stylii will still work as a plain Jane, commplace capacitive stylii when Bluetooth is active when using Astropad.
You’ll get finer line drawing, but without pressure sensing for variable line widths and no palm rejection.
If you want to lay your hand/palm on the iPad’s screen while drawing on your iPad when using Astropad or any other non-Bluetooth stylus drawing/writing apps, you can purchase online special, lycra material based, non-electrical conducting drawing/writing gloves that isolate the electrical impulses from your hand/palm to allow you to lay your drawing hand on the iPad’s screen without your hand/palm leaving stray writing/drawing marks in the sketching/drawing/painting/writing apps.
The Adonit Pixel has ON/OFF/ shortcut buttons.
Has a nice fine, textured pen tip AND a nice rubber grip.
Magnetically charges, has an auto 15 minute shutdown feature ( to preserve battery life ), charges in a hour.
Has both a small USB charger that that plugs into any USB charging block OR you can purchase an optional charging dock.
I find it only lasts for 8-12 hours, but Adonit claims up to 16 hours of continuous use on a charge cycle.
Made of very high quality aluminum materials.
Works with about a dozen of the major/popular drawing/sketching/painting apps (the Pixel/Pixel Pro works with, but currently not “officially” supported with Procreate, but it still works and works pretty well in Procreate ), and about a half dozen of the popular note taking apps, a half dozen writing apps and about a half dozen PDF style/compatible apps.
You have to perform some pairing and setup parameters in each of the Adonit Pixel compatible apps.
You just DO NOT simply turn on Bluetooth on an an iDevice and turn on the Adonit stylus and start writing.
The Adonit Pixel stylus is NOT an Apple Pencil in this regard/respect.
You have to initially Bluetooth pair the Adonit Pixel/Pixel Pro, setup the hand/palm position and in many apps, set up the stylus screen pressure sensitivity for each and every compatible app!
Once you have, initially, done all of this, all Adonit Pixel compatible apps will remember these settings for future use!
Some Adonit Pixel users claimed their stylus doesn’t work, but it does work well IF you properly know how to set up the Adonit Pixel.
Here’s my “up to date”, comprehensive, but still incomplete, list of Adonit Pixel compatible apps for the iPad/iPad Pro models.
All apps listed support pressure sensing and palm rejection from the Adonit Pixel.
Art Studio Pro
ProCreate ( palm rejection improved using special, non-electrical conducting, lycra-based material drawing glove )
Pixelmator ( used to support Adonit, I have an older version that did, not sure about their latest version )
Tayasui Sketches/Sketches Pro ( the new, free Tayasui Sketches School version works with this stylus, but without any palm rejection or pressure sensing, so you need to use a special, non-electrical conducting drawing glove with the Sketches School version for palm rejection ).
ZenBrush/Zen Brush 2
Notability ( palm rejection improved using special, non-electrical conducting, lycra-based material drawing glove )
QuickNotes X Pro
Good Luck to You!