Are my questions so stupid or are the answers so difficult?
Yes!
No, really, there are a few basic issues here.
First, when you're asking about a specific mod, it's better to ask in the thread for that mod. Typically, the person who should be responding to a question is the mod's creator. No one else will be that familiar with the mod in question; most of us don't even have that mod, so can't really answer your issues.
The fact that you downloaded the mod from the in-game mod browser makes it even worse, because many of the mods in there were made by people who have no connection to this board. If there isn't a thread on this board for the mod in question, then there's really no hope of getting a good, detailed answer; we can guess about general issues, but that's about it. If there IS a thread on this board but no one has posted in it for a couple months, that should tell you something as well.
Secondly, many people (myself included) simply don't use the in-game mod browser. The devs have changed the game in fundamental ways several times; at least twice since the game was released, patches have caused previously-made mods to stop working. So if you go on the Mod Browser and download a mod that was last updated in, say, February,
it just won't work. If someone says "I just downloaded X in-game and it didn't work", the answer is almost always that the mod is outdated and there's nothing we can do to help you. (This is why my own mod is not on the Mod Browser; you have to go to its thread on this board, but you'll KNOW whether it's up-to-date then.)
Finally, most of the people on this board are Americans, and your first post was at 3 AM to 6 AM, depending on which part of the U.S. people are in. On a weekday. Not exactly the ideal time to get responses; the weekends are much more active, and the time of day obviously helps as well.
Also:
BTW I cannot use this Dutch republic - mod from the normal game-setup, is that normal?
No mods of any kind can ever be used from the main menu, you ALWAYS have to go through the Mods menu with its disclaimer screen absolving the companies from whatever the mods might do to your game.