Civ5 loads mod in a "oldest to newest" order, with the date coming from when you subscribe/download the mod.

For this mod to work correctly, it needs to load after and other mod you have enabled that adds Buildings and Units!

To ensure this is the case, if you use another mod that adds Buildings and/or Units, you need to unsubscribe from this mod and re-renter the "MODS" menu of the game, which will delete this mod from your Mod's folder. Then resubscribe to get a fresh copy when you enter the "MODS" menu again.

You can also manually delete the mod's folder, named "SMAN's The Lord Mayors (v #)"

If you don't do this, this mod will not know about the Buildings or Units in those mods that load after this mod does. Therefore, they will never be ordered by any Lord Mayor during the game.

It won't break the game, but it might leave out things you really want to see.