Which metadata do you want to import? If you have metadata embedded in the photos, either via EXIF or XMP, Tropy will import all fields that exist in your default template. So if there are specific fields you want to import, you need to create a template with the relevant properties and set it as your default item or photo template.
If your metadata is not embedded with the photos, you can import it into Tropy by converting the data to the appropriate JSON-LD format first. There’s an example in this thread.