I use it,but on my Asus Zenfone 2 with Lollipop 5.0.
Works perfect.
Checked that it's not compatible with my Nexus 7 2012.
I think part of the reason is that your App is connected to your device with the phone number that you used to open your Capitec account.
So maybe the app is totally incompatible with tablets and only works with phones.