Open the mounted drive in Finder and look for the font files.
If the extracted files are already .ttf or .otf , no conversion is needed—you can install them directly. However, if you find .dfont or "suitcase" files, follow these steps: Using Online Converters
Sometimes fonts are buried within nested archives. You may need to open a .pkg file inside the DMG, then a Payload file, until you find the Library/Fonts directory.