This article (and the whole section of documentation, that starts with https://docs.cs-cart.com/marketplace-addons) refers to the add-ons of the CS-Cart Add-ons Team that was closed on 19-th of April, 2024. There is no longer support for any of their add-ons and they are no longer updated. The last version added and tested for compatibility was 4.18.1.
So if you are looking for the default add-on that comes with CS-Cart Multi-Vendor by default, please have a look at the article I linked to earlier.