D-Link AC3200 Ultra User Manual page 167

Section 5 - Applications
Connecting to your USB Storage Device from a Mac:
To access your files, click on your storage device and press the connect button.
The drive's contents will be displayed in Finder.
If a login prompt appears, enter your DIR-890L's web configuration utility's username and password you created when you set up your router.
D-Link DIR-890L User Manual 162