How to copy files from remote server to external HD without using local disk

I am trying to copy files to an external HD on macOS Sequoia The remote server (WebDAV) mounted via Finder -> Go -> Connect The problem is that using sync, the local Machintosh HD runs out of space during the copy. - I tried to avoid caching or setting tmp folders to the external HD, but whatever I do, the space available on the local HD keeps going down during the copy. - The local HD went from 20GB free to 0.5GB during the file transfer, till all stopped because of it. This is an example of the rsync command I use and my shell is zsh: rsync -hvrPt --temp-dir=/Volumes/USB_DRIVE/tmp --max-size=1000M --no-partial /Volumes/dgk.data.uu.nl/research-***/***/***/*.fast5 /Volumes/USB_DRIVE/fast5_pass --temp-dir --max-size and --no-partial were used to avoid clogging my local HD during the transfer, but it didn't work. How can I transfer 500GB from a remote server to a USB drive without using the local HD space (only 20GB free)???