I have connected my Iphone and can see it in the sidebar. The only message i get is : preparing to import from ... Iphone. Nothing actually happens.

Did you follow the steps mentioned in the related article above?

Transfer photos and videos from your iPhone or iPad to your Mac or PC - Apple Support

Depending on the number of photos, it may take a while until the Mac has gone through all saved photos on your iPhone, and you can press the button to import them.

You can download the photos from iCloud onto your Mac, check this article and the "Photos and videos" section about how to do that:

Archive or make copies of the information you store in iCloud - Apple Support

How many photos have been saved on your iPhone?

Are you also using iCloud Photos?