1. Use a jar file. Put your lsp-fatjar.jar file path there. Make sure you have a java executable in the Path (recommended) or in java.home key in the settings json.
2. Use the jlink version of Aya. Put the aya-lsp (or aya-lsp.bat if you are on Windows) file path there, which is under the bin folder of the jlink distribution. In this case, you don't need to have a java executable in the Path.
Then, open a directory that is an Aya project (see project-tutorial). Open any .aya file, you should see some basic highlight (keywords, comments, etc.). Wait for VSCode to activate the extension, and hit Ctrl+L Ctrl+L to load the file. At this point, you should see advanced highlight (type names, constructors, etc.), with clickable definitions.