Well, I can't read the text, since I am one of those "English only" people (I used to be able to do elementary school German and could fake baby-talk Spanish, but way out of practice), but from the looks of the "style" of the box, that is one of those "This program has been blocked" kind of messages with a "we have protected you from possible harm" claims... This is where the folder matters, so just to make certain, you cannot have the game installed in a "Program Files" folder, whether under a Steam structure and Steam Library, or a Ubisoft structure and their "Library" style of folders. You must have the game in a folder that you created, such as "C:\Games \ Steam..." or "C:\Games \Ubisoft..." In that way, Windows will not interfere with your attempts to alter the files.
Secondly, when you go to run the patch on the un-modded game, right-click on the patch's executable file, and choose "Run as administrator", which is what looks to be your problem, going by the look of the message box pop-up you have there. One other thing to look for, is the fact that some of the install routines (I can't remember which) will set the "important" files in your install to Read-only, so you might need to navigate into the game folder that you are attempting to update, press the <Ctrl> key, and while holding that, press the <A> key to "Select All". Right-click on any one of the selected files, choose "Properties" at the bottom of the resultant context menu, and on the first "General" tab that opens, clear the tick box for "Read-only" under the "Attributes" section. You will then be asked if you want to apply that to all files and sub-folders, and you do want to, which when you click Yes and OK, will then take a minute of two to run, and then your files can be written over by the patch.
Thirdly, and this is Mr. Obvious speaking here, but you cannot make a v1.5 game into a v1.4 game by applying the patch. Only version 1.3 and earlier. You also do not need to "step through" the versions. If you have a v1.0.1 original disk version, you can apply the version 1.4 patch, and it steps all of the way up to v1.4 with that.
Fourthly, with Mr. Obvious again, you cannot apply the Ubisoft v1.4 patch to a Steam game. Steam will not take it, and you will see a pop-up stating that the game is already updated to v1.4 - even though it is not. Steam has their own way of doing that, and that is for you to purchase their version of the "U-Boat Missions Add-On" for an additional fee. You cannot use a Steam update with a Ubisoft game, and you cannot use a Ubisoft update with a Steam game...
Let us know how you get along, but my guess is it is the Administrator rights need to be applied as you run the patch.
