[2020] Modern City DLC Not Working

Make sure to zone the right type as well. Modern City Center is high density commercial buildings (the dark blue zone type). And ofc you will need to have commercial demand for them to build.

This video shows step by step how they work, which might be handy, to make sure you haven't missed something, since the buildings are enabled for you. :)

https://youtu.be/eEQNOXzTkfM?t=65

If that still doesn't work, try adding the launch option -noWorkshop to Steam.

https://support.steampowered.com/kb_article.php?ref=1040-JWMT-2947

Originally posted by Mister Dank: Wait... it only works on commercial buildings?

Yup, it's a style for high density commercial. The CCPs are always smaller packs than the main DLCs and don't cover all zoning types (some of them contain unique buildings instead of zoned ones).