It's all command line. There's no web UI. You need to connect to the management serial port. Page 25 of the installation manual:
https://downloads.avaya.com/css/P8/documents/100097603
Then you can set the switch's IP address. As the manual says, VLAN 1 is default reserved as the management VLAN (the one from which you can access the switch's management interface).
This is a real managed switch, not a web-based "managed" switch like my Netgear.
Here's the operating manual, in case you hadn't gotten it.
https://downloads.avaya.com/css/P8/documents/100097604