You can choose to download the app 
https://apps.apple.com/us/app/icrwy-lessons-i-can-read/id1617743018

But PAY for it here.  (or here if in Australia https://www.speechsoundpics.com/product-page/icrwy-lessons-app-for-multi-users)

Use on up to 25 devices GB £75 per YEAR
Use on up to 50 devices GB £125 per YEAR 

Ask for a bespoke quote for more than 50 devices, or to give parents access etc. 

Simply type the email you want to use for login and we will set it up for you. 

Although we will remind you when it is due to expire this is not automatically renewed. The payment covers a 12 month subscription.