I just downloaded the modpack, and it says there are mod version mismatches. Only razi-protoco is marked in red; everything else is fine. I haven't changed anything—I just downloaded the modpack, and it won't launch.

Thats becuase ya have to manually download old versions of Krastorio 2 Spaced out and it's assets. Due to its new updates being for the experimental version of the game and having a lot of bugs with other mods

what is the good version of krastorio ?

If my understanding is correct and I am not fully sure mind you. The razi protocol has >= and <= indicators for version requirements

yes i see that but the things that i cannot retrograte kr2 asset 2.0.5 to kr asset 2.0.3

Oh the mod page is how I downgraded my own. There is a segment for all previous versions in the download tab.

in my factorio folder i dont see any ''mods'' page how i do ? i already tried to search with the searchtab from my folder manager but i see nothing

You can download older versions of mods right here on the mod portal from your web browser. Just go to the mod you want to downgrade, click the downloads tab, download the version you want (do not extract the .zip) and place it in your mods folder for Factorio, which is located in: AppData\Roaming\Factorio\mods
If you have multiple versions of a mod installed, then in-game, you can select a version of the mod you want from a dropdown menu when looking at the mod in the in-game mod manager.