If there's an option to create new folders on the GOG Galaxy application, I don't frind it.
There should be one, to organize the games into categories. Like "unplayed", "playing" or "finished", or create game collections.

Here's the Galaxy forum: https://www.gog.com/forum/general_beta_gog_galaxy_2.0#1739103514

NB. I'm not using the latest version of GOG Galaxy.

When going to a game page in your owned games, on the top toolbar there is a settings button. From there you can open Edit... and assign tags to the game. After that you can filter or sort your games in Owned games by the specific tags you have assigned.

Here's an improvement: Don't try to make GOG galaxy appear modern when your demographic plays retro games and likes older technology.

Here's a great improvement I think many of us will agree with: 🗑
Bin it.

You can create collection already in Galaxy - they are caled bookmarks. From the game settings -> Edit ( tags) or you can right click a game and assign tags-< add tags. You create a tag then sort the game(s) with that tag and pin it with the the button in the top left corner next to the arrows. This will add it as a bookmark on the left side.

nevermind. Posting failed for some reason.