Canon i900D printer driver for ElCapitan

Canon has not released any drivers for the i900D since 2014, and these last updates for Snow Leopard users. Not surprising, there is no i900D driver support in the 2017-07-06 Canon Printer Drivers v3.4 for OS X on the Apple downloads site either.

Your only option is the GutenPrint for Mac OS X v5.2.13-pre1.dmg (not a direct download link) as GutenPrint shows support for the i900D. I cannot vouch for the quality of that support. Your mileage may vary.

No. Canon does not offer it. Contact Canon and see if they can provide a solution.