I believe your Chromebook runs the Android operating system, so if the zip file contains presets in the XMP format, you can open any photo, select the Presets tool, go to the ... button at the top, select Import Presets, and they'll be imported directly as presets in the Yours tab.
If, however, the presets are provided in DNG format inside the zip, then you'd need to unzip it to show the DNG's and import them as photos, as Johan said.
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