Tips for playing Epic Games Store workshop maps
It would be a problem for you to download the files directly from Steam, which means you're going to have to get the files from the creator directly (Lethamyr has said we will be able for your website to download maps: update: /lethamyr.com/mymaps), other sites (like this mod site) or friends who are lovers and have access to Rocket League. I'm glad to add other references if anyone has. Update: you can now download a workshop-link to the search bar, then simply click on the download. (If a ZIP folder contains the file, don't forget to unzip it!)