Tested successfully with version 2023.1.3 as well.
Should you get the "unsupported version" message showing up in the console, then I am afraid you're running (as the message implies) an unsupported version of Cinema4D.
It's working for me with version 2023.1.0
1. "Search Material" being a Python plugin its welcome message shows up in the Python console window
2. The plugin is running as the additional "Search" menu item is present in the Material manager.
3. Pressing the Search menu item does open the plugin's option window to accept user input for searching and filtering.