CourseWalk V1 is not compatible with Android 11 and has therefore been removed from the Google Play Store. Please upgrade to CourseWalk V2 if you are using Android 11 or later.
However, you can still download and use CourseWalk V1 on older versions of Android if you previously purchased it. Click this link to download CourseWalk V1: https://play.google.com/store/apps/details?id=com.coursewalk.coursewalk