Keymander App in the Works
It looks like your device does not support OTG which is required to pass data between your phone and the KeyMander. Without that data transfer, the KeyMander cannot communicate with the tablet. Here are some articles.
Your device is not listed as OTG compatible. The Tab 3 8" and larger tablets do, but your doesn't seem to. It seems that this spec is not easy to find for the device and many people purchased this were being told it does support OTG. I do not see OTG listed on Samsungs specs. I don't know why they wouldn't list that. Frustrating!
I suggest trying this with an Android device (Android 4.0 or higher) with OTG support since you do not have a computer. Check the list in the link above to check if OTG is supported by the device.
Here are the requirements so you can double check your devices: