This is probably due to the content pack missing from your server. It needs to be added to your servers workshop collection, which is downloaded everytime you startup your server.
Most modern hosts has a field on their control panel where you define the workshop collection you want your server to download.
Only custom models and materials are used for this script and the script content can be found at: https://steamcommunity.com/workshop/filedetails/?id=1734833080
Make sure to add this to your servers workshop collection as well.
