Beta version of the mod, does not yet include the new map.
1) After extracting the mod, you will see a folder called "copy content to same folder as alexander exe".
The folder it refers to is probably located here: C:\Program Files (x86)\C:\games\steamapps\common\Rome Total War Alexander
Make sure to copy the folder's content, not the folder itself!
2) Run the game using the command line switches: -mod:alx -show_err
3) Credits can be found in "...\copy content to same folder as alexander exe\alx\credits.txt"