To get a dvd copy of SH5 go to Amazon.com and do a search for Silent Hunter 5 - Battle of the Atlantic. You do not want any downloads of the game.... that's the same as getting it from Steam. Downloads of Sh5 are a waste of time and money IMHO.
Have you done this, as it's important for a non corrupt mod installation with JSGME?
When you get a mod in a zipfile, open it with 7Zip and Extract the mod folder to your desktop. Click on the folder to open it. With most mods you'll see the mod and a document folder or readme text file. Read what's inside it and either save the document folder to someplace outside, or read it and delete it. Only import the mod folder with JSGME to the Mods foldler in SH5 and activate it. The document folder or readme files shouldn't be imported as they can and will corrupt the mod yo want to install.