DIAGNOSIS You're probably stuck in the maze of Brother software options. You don't actually need the full software suite to do a simple scan.
FIX The most reliable method is to use the Windows Fax and Scan utility (if you're on a PC). Make sure your printer is connected to the same network as your computer. On your PC, open 'Windows Fax and Scan'. Click 'New Scan' on the toolbar. Your Brother printer should appear as a source. Select it, choose your settings (color, DPI, file type), and hit Scan. For Macs, use the built-in 'Image Capture' application. It works the same way.
IF THAT DIDN'T WORK Your computer might be missing the proper TWAIN or WIA driver. Go to the Brother support website, download and install only the 'Scanner Driver' and 'ControlCenter' software for your model. After installing, you should see a 'Brother ControlCenter' icon on your desktop. Open it, and you can set up one-touch scan buttons to a folder or email.
HEADS UP Avoid the massive 'Full Driver and Software Package' unless you need all the extra features. It can be bloated. The scanner driver and ControlCenter are usually all you need for basic scanning.