You are about to download PPMXL, a catalog of about 0.9×109 stars. For details, see the PPMXL info in the GAVO data center, which is also where you'll find column metadata and other ancillary information. Unless you have a project that requires a lot more smarts on the whole catalog than ADQL gives you, our advice is to use PPMXL through TAP service.
In case you really want the dump: it is 43.5 GiB of gz-compressed ASCII. On a line with a constant throughput of 10 Mbit/s, downloading this will take roughly 10 hours.
In case the transfer is interrupted, you can probably resume where you left off by changing to your download directory and running a command like:
curl -C - -O http://vo.ari.uni-heidelberg.de/ppmxl/dump-for-web.gz