Switching computers

jordaparne  You can transfer the files like you'd transfer any other data: with an external device or via cloud storage.  For the external device, it will need to be formatted as exFAT in order for both OSs to read it.  For cloud storage, you can use a free service (Google Drive if you like, and both iCloud Drive and OneDrive are accessible in both OSs) if you don't have too much data to transfer.

I would strongly recommend zipping the folders before transferring them.  This will protect the files from getting corrupted in transit.  It's especially important for mods and custom content—we've seen cases where all of the files show as corrupt on the new computer.  To zip a folder in macOS, right-click it and select Compress; to extract in Windows, right-click and select Extract.