Maybe you are behind a proxy server which causes problems or there is some other problem why you can not connect to our server. I once heard that the “Great Wall” caused problems. Maybe you should talk to your IT admins.
Have you followed this thread:
For the resampling, as long as you don’t have the latest modules it might be problematic to resample S2 data.
But in general you can do it.
Using a shapefile to crop the data to a certain area is not easy. In the GUI you can define a geographic bounding box and from the command line you can specify a polygon using WKT. But this will cut out also only the bounding box of the polygon (because images have to be rectangular). You can mask the data afterwards by using the land/sea mask processor.
You will find several examples in the forum how to do this.