A clean environment
First of all you need a working installation of napari, you can refer to that webpage for more info https://napari.org/#installation .
It is strongly recommended to work with virtual environments (such as virtualenv or conda). You can create a new environment especially for your work with napari-deepfinder. This is really useful and advised, especially because napari-deepfinder will install a lot of dependencies (including deepfinder and it’s dependencies).
Installation of napari-deepfinder
The general purpose guide for installing napari plugins is available here.
Basically you need to start napari and go in the plugin menu. There you will find the Install/Uninstall Plugins entry, which once clicked opens a new dedicated window. There you can either:
Enter the name napari-deepfinder
Enter the url https://github.com/deep-finder/napari-deepfinder
Drag and drop the folder of a downloaded copy of the source code of the plugin