$ zsync http://cdimage.ubuntu.com/ubuntu-server/daily/current/zesty-server-amd64.iso.zsync
#################### 100.0% 144.7 kBps DONE     

No relevent local data found - I will be downloading the whole file. If that's not what you want, CTRL-C out. You should specify the local file is the old version of the file to download with -i (you might have to decompress it with gzip -d first). Or perhaps you just have no data that helps download the file

What I *think* it’s trying to say is something like: ”No relevant local data was found, and therefore the entire file will be downloaded. If that’s not what you want, use Ctrl-C to abort. If you do have local data, you should specify the location with -i. If the local data is compressed, decompress it first.”

Also, the ”verifying download…checksum matches OK” message (after downloading is finished) could do with capitalization and whitespace: ”Verifying download… Checksum matches OK.”