When installing a custom story in Amnesia: The Dark Descent, you may encounter various problems. First, compatibility is a major concern. The custom story might be developed for a different operating system than yours, or it could be designed for a different language version of the game. Second, if the download is incomplete or corrupted, it won't install correctly. This can happen if there are network issues during the download. Third, if the custom story has complex file structures or requires additional software to run, and you don't have those, it won't work. Additionally, if your computer doesn't meet the minimum requirements for the custom story, it may also cause installation or gameplay problems.
Well, there are several things that can go wrong. For example, if your game has been modified in some other ways, like with other mods installed, it might conflict with the custom story installation. Sometimes, the file permissions on the custom story files can be incorrect, preventing the game from accessing them. And, as I said before, the wrong version of the game in relation to the custom story can be a big problem. You also have to be careful about the source of the custom story. If it's from an untrustworthy site, it could be corrupted or contain malicious software.
One common problem is a version mismatch. If the custom story is made for an older or newer version of the game than what you have, it may not work. Another issue could be incorrect file extraction. If the files are not properly unzipped or moved to the 'custom_stories' folder, the game won't recognize the custom story. Also, some custom stories might have dependencies that are not included in the download, causing it to fail when you try to play it.