In the grade page (which is what your image shows, not fusion), you drag your OFX plugin to a node. Then the controls should be available. Be aware that only the studio version of Resolve includes access to all OFX plugins. If you have the free version, you might not be able to use that sharpen plugin. However you can use the built in sharpen/ blur options. The icon next to the tracker opens up the blur/mist/sharpen tool