you can try to verify the integrity of game files and if that doesn't help, you can try a clean reinstall as described in my guide on reddit about common startup problems with version 1.29

Does this help?

As I understand it, these DLCs were given to me for free (“Rights of Man”, “Art of War”, “Common Sense”) but for some reason I don’t see them in the game for example sale of ships

They shouldn't exist as separate items any longer - they are as integral to the game as the province geography and culture groups.

Messaggio originale di Fame of Rome:

As I understand it, these DLCs were given to me for free (“Rights of Man”, “Art of War”, “Common Sense”) but for some reason I don’t see them in the game for example sale of ships

Did you try the things which I suggested? Also make sure that the main menu displays the version number 1.37.5

All DLC are already installed in the game files and you just need to first start the game via launcher, click on the dlc in the launcher and enable/activate the ones you bought.

There is no special "download the DLC here"-button. When i get a new dlc, the game automatically download the dlc. It happens like a patch: you don´t have to do anything. You then can see the dlc in the launcher. There is a area just for that. And if you play the basic game, you can see all your installed bought dlcs in the start page. The ones you own are colored, the ones you do not own are grey.

It is, as MarVerine wrote: the dlcs are already installed in the game. But you actively only use the ones you own. If you play multiplayer, you then can use the dlcs from others.
In other games from paradox, like stellaris, you can even see, how the computer players use the stuff from the dlcs against you. For example, when they introduced the titans there, i suddenly had to fight against them, but could not build them myself.