We are aware of an issue where some customers can't login/stay signed in with their Paradox account which then results in being unable to play multiplayer. We released an update early on the 22nd of September that we hoped would solve it (you can read more here: https://forum.paradoxplaza.com/forum/threads/server-update-notification-sept-22.1423886/) but it seems that wasn't the case >.
We now think this is an issue with dual CPU systems.
CPU or GPU slightly below the minimum requirements should not cause a crash like this. If that is confirmed there will be a hotfix soon to address that problem.
Sorry about that!
In the meantime you can revert the game to version 1.03 in the Steam Betas tab for the game, which does not have that problem.