Upload through the sharelink?

Hi,
if I have a sharelink and the user have the write and upload permission why can’t this user upload a file with this sharelink?
The user have to login in the complete login. And there it is a little bit confusing for normal users to find the right folder because they see his own library first. This is not a really well UX.

How can I give the user a possibility to upload files with the sharelink?

Best