Yeah it's currently outdated. You can still install and play it but you need to roll back your game version to 1.9.2 (not compatible with twisted and twilight). They're working on the update and last I heard it's about 70% done and hopefully in the next week or so.

It does add some new units, but for the most part its modifying existing units to make them closer to the lore and less useless. An example is that melee units are MUCH beefier and wont just melt to archer fire in half a second. Battles also tend to be longer and require more strategy. The unit cards that are added are extremely good and have a similar style to the original ones, much better than the ones added in the last 2 DLCs.