Steam doesn't always fulfill our desires of sharing maps and mods, thus we have to take it into our hands to resolve it. Even more so, we, the creators of these maps & mods who get blamed for them not working. Not every issue is caused by the poster, sometimes it's steam's fault. Remember that before you chew into someone who posted a mod or map on the workshop. :)

Pre-prep process - Ensure you're in administrator mode. Otherwise you won't be able to use this map pack collection even though you subscribed to it.

-Locating the map-
Maps appear in alphabetical order and sometimes we just overlook them. So, just go into your 'Additional Maps' and locate the map you're looking for.

-Having problems getting the map to work-
If you're having a problem getting a map or maps to work, follow this easy step process.

My Documents > My Games > Civilization 5 > Mods > Mass Effect Homeworlds > Build > Mass Effect Homeworlds > Locate the map(s) you're looking for <-- Take this file or files and move them into the folder 'Maps' which is located in the Civilization 5 folder. After that you should have to maps in your additional maps in game.

If this doesn't work, then there is only one other solution. Downloading the map pack from a third party website. I currently do not have a third party website where I house these maps and likely I may never have one. The reason is because these third party websites are not always as trustworthy as they seem. So, while to some this may not be a big deal, to me it is. I don't want anyone to get a virus just trying to play on these maps. Even I, Dunabar, don't feel these maps are worth getting a virus over just because you had to download from a third party website.