May I know what is your Metronic version please share the 403 error using https://imgur.com/ ?
If you haven't compiled the theme assets please follow this guide.
Please note that the build tools are used in your dev environment only just to compile the assets folder and in production server you just need to deploy the compiled assets without needing to install the build tools there.
I download and use the html project (Metronic 8 - Demo 20). I did looking in United Palms Pro graphics template and i didn't find. I think is not create because i only found for 404, 500 and 505 error.
I found only these errors: https://imgur.com/mkTwwXn