I had the same problem as many seem here with the save not functioning at all.Everething was as it should expected.Install folder,UAC,Autosave,script.But the Devs seem not to have a solution.It seems the mod somehow corrupts the save or pereferences file of the modfolder campaigns.So see what i did and reply if it worked for you also.
First launch the campaign you want to play lets say Sparta.Even if you cannot save, play for at least 1 turn.Then exit the game.Next go to the Installation folder of Rome in your HD and find the folder that has the name of the campaign you played, in this case "Play_Sparta".Inside it you should find two folders,Save and Prerefernces.Delete them.Carefull NOT the Data!Just these two.OK now relaunch the game with the same campaign.Inside the game dont start yet the capmaign but go to options and make at least 1 change in the grafics options like resolution change or level of detail of trees.Anyway you could change the options to your likes so do that but if for some reason you didnt change them you must change at least 1 of them.Launch a new campaign without exiting the game.You should be able to save now.If you have the same prob with other campaigns repeat the process.With this you just force the game to make a new and clear save and pereferences files.