It is probably due to the fact they took it off Steam, prior it was downloaded through Steam, now its through Epic. I have not found a way to get any of the practice maps after they took it off the Steam store.

I found out about this map today and had no troubles.

1) Subbed to the map.
2) Launched RL
3) Clicked Play -> Play Offline -> Workshop

I have subscribed to this map, but when I go to rocket league and then play offline the workshop thing doesn’t come up. Someone plz help. It just comes up w exhibition and season

You can still play custom maps (even on Epic) by using Bakkesmod. They have a plugin on their website you can add which allows you to download and install custom maps within the game itself, using any key you wish to set. It's called "Workshop Map Loader and Downloader" and you'll likely see it on the plugin landing page in the Top section.

Happy training.

引用自 Flikety：

I have subscribed to this map, but when I go to rocket league and then play offline the workshop thing doesn’t come up. Someone plz help. It just comes up w exhibition and season

Same man... same