If you don't see the VST or AU plugin you want to use in the plugin list box, it's likely that the JamKazam app is not scanning the location on your computer where the plugin is installed. This is a common issue for plugins with all audio software apps. Apps do not scan your entire computer for plugins. They typically scan the default location where these plugins are "supposed" to be installed (according to Steinberg), plus a list of other directory locations where the user manually asks the app to look. So basically you will need to tell the JamKazam app where to look to find the plugin you want to use if it has not been installed where plugins are supposed to be installed. Following are instructions on how to do this.
First, you'll need to figure out where (in what directory/folder) on your computer the plugin has been installed. We can't answer this question. You'll need to figure this out on your own. It's different from one plugin to the next, depending on where the maker of that plugin decided to install it.
Once you have determined where the plugin is installed, click the "manage audio plugins" yellow text link, and then click "manage folders/paths to scan for plugins" option (pictured below with arrow).
Please note that all the screenshots in this help topic are for effect plugins vs. MIDI instrument plugins, but the interface and instructions are close to identical, so you should be able to follow the instructions in this help article regardless of which plugin type you are working with.
A dialog box is displayed (pictured below) that lets you manage the locations where the JamKazam app will look/scan to find plugins. Click the Add Scan Folder button (pictured below with arrow) to add the location where your plugin is installed.
A standard navigation dialog box is displayed. Use the normal navigational controls to go to the directory/folder where your plugin is installed, and then click the Open button (pictured below with arrow) to choose this directory/folder location.
The "choose a directory" dialog box will close, and you will see that this location has been added to the list of locations to be scanned. Close the "manage plugin scan folders" dialog box, and then run another plugin scan using the menu command explained earlier in this help article.
Now you can click open the Audio Effects or MIDI Instrument list box, and you should find your plugin listed and available to be selected for use.