Does the following link show the app you installed?
https://play.google.com/store/apps/details?id=jp.co.canon.bsd.ad.pixmaprint&hl=en_US
Yes, that's right.
Does the Android tablet otherwise successfully connect to your network and the internet?
No. it doesn't. This is the problem
Are other computers/devices able to print to the Canon inkjet?
Yes, they're. My laptop HP Notebook (with windows 8.1) is able to print to the Canon inkjet. Also my PC but by USB cable.
Does the Canon inkjet have an assigned static IP address?
I don't know. I'm going to check.
Take a second look at how the App SELPHY is configured on the Android tablet.
ok.
If all seems to correct then the original install may be buggy or corrupted.
Reinstall.
I found the following installation "guide":
https://canoncanada.custhelp.com/app/answers/answer_view/a_id/1022986/~/printing-from-an-android-smartphone-(wi-fi-function)-(selphy-cp1300)
Doublecheck your installation accordingly.