v1.3 needs to be updated to v1.4. In downloads there is a free upgrade to v1.4 you need to install.
But first, check out the Tutorial on how to install SH4 if you got it from Steam.
Even though v1.4 will give you a playable game you really should buy v1.5 the U-Boat expansion. It has many improvements for the US vs Japan campaign and most mods require the v1.5 U-Boat expansion.
First though, install SH4 using the instructions in the Tutorial.
http://www.subsim.com/radioroom/show...postcount=5223
http://www.subsim.com/radioroom/show...21&postcount=3
http://www.subsim.com/radioroom/show...25&postcount=7
It will be worth it, have patience, I know it's a lot to do.