Hello! I am modding on a new device, and with this new mod I have a small problem. I cannot update this mod even if I have installed the mod through the Steam workshop, so how do I put my mod (the files) into my new device?

If the mod is installed both via Steam, and locally, I believe the game fails to load either as there's two versions of the same mod (which shouldn't happen)

How do I fix this error?

(I mean like, how would I have only one version of the mod and at the same time be able to update my mod)

Always use your local version (the in My Documents/Paradox Interactive/Hearts of Iron IV/mods) and never the Steam version. 

You should still have the same checksum as someone who downloaded from Steam; allowing you to play MP, and this will ensure you can still update your mod after initially adding it to Steam