We'll need to see the logs, which you unfortunately can't attach here on Steam. The best place to get help is to make a post on our official support forums:
https://forum.paradoxplaza.com/forum/forums/support-bug-reports.879/Include any details of what happens, like what you're trying to do when it crashes, what error you get (if any), if you use mods and what you have tried already (so we don't have you go through things twice).
If you get the error saying "Oops the game has crashed..." then it mentions a folder with 3 files, which we will need.
If you do not get that error, we will need the output_log.txt (called player.log on Mac and Linux), which is found in the Cities_Data folder.
Both the Cities_Data folder and the crash folder are found with the game's local files. The easiest way...
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