I got myself an ipad recently, which works quite fine, but printing to my canon mb5150 was a pain. The printer supports airprint, and I could try to print on the ipad. But then it would either tell me that "the printer is busy", or I would get an error on the printer, requiring to reboot the printer.
I also installed the canon app on the ipad, without any change. But there was a button in the utitlities section leading me to the web ui of the printer. I guess one can also open it directly. And the last entry on the main page "Für sichere Kommunikation" / secure communication leads to a page that allows to install the root certificate. Once that is installed, printing works fine.