By default DHCP is active on Audience, no need to set static IP address on your PC.
Don't connect over the "internet" port, it will not work (default firewall blocks it), only connect with cable to 2nd Ethernet port .
The best is to use the Mikrotik tool "winbox" . You can download from Mikrotik download page (but works only on Windows systems).
With Winbox you will be able to connect on "MAC" level to the audience, thus no need to setup any special IP address etc.
Once downloaded, connect to Audience and open winbox. Check the "neighbour" view, if you see a device.
Then click on the MAC address and see if you can connect to the device.
If that does not help, either return it, or depending if you want to try, do a net install (rewrite latest firmware to the device).
I would recommend the "stable" version, which is what I am using on my audience.
I like a new challenge, I migrate to ROS7...
no way, finally I stay with 6.48! I am NOT crazy