The SMB command can be confusing. Try it this way.

Get Finder on your screen

Select Go from the Menu Bar
Towards the bottom select Connect to Server
In the box that pops up enter
Code
SMB://xxx.xxx.xxx.xxx
You should have a screen asking for a password, you should probably just hit the "Connect" button.

You will now have your MC200 showing with the file folders.

Now go to Roon and it should find your Directories. (I dropped Roon so I can't still walk you thru those steps.)

Jim
Wilson Alexandrea X2 Series 2
D'Agostino Momentum M-400 Amps & Pre Amp
dCS Vivaldi DAC, Upsampler & Clock
SME 20/3 & Esoteric E-03
Transparent OPUS SC & Interconnects