eSpark is accessed on all devices, including iPads, at espark.app. A quick way to direct students to eSpark on iPads is by adding a web clip to the home screen of the iPads. Web clips are icons on iPads that look just like apps but open a website in the browser.
You can install the eSpark Web Clip using your MDM. Here's a configuration file you may be able to use to import the eSpark Web Clip.
You'll want to follow these guidelines:
The Label should say "eSpark"
The URL is "https://student.esparklearning.com/student/"
The Icon can be found here and is also included below.
The Full Screen checkbox should NOT be checked.