Unfortunately, the Brother MFC-5890CN does not appear to be an AirPrint compatible model, which is what you need if you want to print directly from an iOS device like an iPhone or iPad.
Check the list of compatible products in this Apple support document to verify.........About AirPrint - Apple Support
What might work is to try a third party application like Printopia to see if that will allow the iOS devices to print. There is a free trial for Printopia, so you will know whether it will work or not before you spend the $20. More info here.........https://www.decisivetactics.com/products/printopia/