Unless you're looking at a Bonus Mod for subscribers only, you should be able to download anything else. JSGME is not one of those. You of course have to be logged-in to download. The download site can be rather busy, so just give it a whirl at a different time of day. Also, sometimes a browser change helps. If I can't get a good link with IE, I'll try FireFox, and be in like Flint. Cleaning out your browser's cache is all it takes sometimes too. Look at my 'stats', and notice that I've got downloads, and haven't been able to pop for a contribution just quite yet.
There should be a few Webster mods that'll work. I just can't remember if GFO has a 1.4 version... but I do know that a couple of the Fall of the Rising Sun versions do, like v1.2 & 1.3. They do have some "bugs" though that'll get you every once in a while (like a few other mods, and even Stock do), so be sure to save and save often, and with a "new" file name for each save. Don't overwrite old saves.
Also, you could watch the Steam Store site, and Amazon for "sales" on the SH4 v1.5 UBoats add-on. They'll usually run $10US, but hit every once in a while for $5. Going through the SubSim Store at:
http://www.subsim.com/store.html
is a way to contribute also, since they get a small commission on the sale. However, it does not look like much of anything SH4 Uboats is available at this time. I don't think they're got an agreement with Steam from here.
Just be sure that your install of Silent Hunter is not in the Program Files (x86) folder in Windows, due to Windows UAC "protecting" you from yourself. It gets very difficult to install "mods" when the game is there. It's doable, you just have to do all the work that JSGME does for you automatically.
oh, and hey, welcome to SubSim!
- oh! I see your "download" has updated. Kuhl.