Ok same with mine. App does not appear on my S2's playstore but does in my Nexus 5.
I tried it out on my Nexus 5. It seems to do the same basic things as the built in Device Maintenance in S2 Settings. I guess Samsung wants you to use their software and has not given permission for compatibility for this device. Or the permission is delayed which has happened to me before with other devices and apps.
One way around is to load on one device, back up the apk and try sideloading onto the S2. I have done this before