In the downloaded package, open the "packages" directory. There should be another one called "maps". Open that.
You should see a cgz file and maybe a cfg file for each map. Put these in your "packages\maps" folder in your AC home directory.
If there are custom textures or mapmodels, they'll be in the "packages\textures" and "packages\models\mapmodels" folders, respectively. Put them in your (you guessed it) "packages\textures" and "packages\models\mapmodels" folders, respectively.
You can do this in the "mods" folder as a mod, too, if you wish.
You should see a cgz file and maybe a cfg file for each map. Put these in your "packages\maps" folder in your AC home directory.
If there are custom textures or mapmodels, they'll be in the "packages\textures" and "packages\models\mapmodels" folders, respectively. Put them in your (you guessed it) "packages\textures" and "packages\models\mapmodels" folders, respectively.
You can do this in the "mods" folder as a mod, too, if you wish.