Do you have Lightroom Desktop (the cloud version) or Lightroom Classic? The first stores all images in the cloud and you cannot accomplish what you want as it will not retain the original folder structure and will simply copy all images and upload them. The second will do what you want by importing using the "Add" option, which will keep your folder structure intact and will keep your images in the same spots. It will not upload them to the cloud though.
It's the desktop version... I justr installed the 7 days trial stuff.
You said it will not retain my forder structure and copy files to the cloud, but it will not change anything on my HD ? It will take files and COPY them to the cloud ? so I still will have the same folder structure ?
It will first make a copy on your hard disk and then upload them all. It will delete the local copies after a while but will leave all the original files in your folder structure. The original folder structure won't be reflected inside Lightroom cloudy.