The principle of this method is to retrieve and run the game under version of yr 2019. You can refer to the below reddit website for the details.
https://www.reddit.com/r/Steam/comments/611h5e/guide_how_to_download_older_versions_of_a_game_on/

Before following the below steps, it is recommended to save a copy fo gave same in below location:
C:\Users\Username\Documents\my games\DistantWorldsCode

First, run the steam console by pressing Win+R and type the following:
steam://open/console

Next, type the below order:
download_depot 662240 662241 4669742890279378883

After download is completed, copy the content from Steam\steamapps\content\app_662240\depot_662241 to Steam\steamapps\common\Epitasis

Then, delete the save file in below location and start playing the gaming in the beginning (I'm not sure is it necessary, I get the achievement with the below save file deleted)
C:\Users\Username\Documents\my games\DistantWorldsCode

For reference, I get the achievement after placing the 8 cubes

Refer to the forum, it seems the Hidden Gardens achievement is not worked since yr 2020 and it is still not yet fixed. Hope this guide can help you for getting the Hidden Gardens achievement and thanks for your reading.