99% of the time i find its 100% of the time due to a directory write protected by AV / permissions or parttition / virtual drive / location wierdness.. or a name missmach due to OS or language or capitalization..
best bet is to try and look at the logs and see what the file its trying to download is.. then crossreference it with springfiles maps by the same name and see if the wording is correct.. then if thats not the problem look into your router and or av firewalls and see if they are blocking things... lastly you should probably first do a location check to see if the game has a sane working enviroment and not some obscure nested vurtual machine or something.
also you have write permission and space on your hardrive.. hmm
if its none of this stuff.. then do a steam verify integrity of game files and wait for more advice
oh and deleting zerok cache can sometimes help
does this download as ivands_pocket_world_v1.sd7 ?
https://springfiles.springrts.com/?type=2&filter=8ede69c37d20cc7d2a6f574d40b39bb4you dont need to run or play it but check the name.. sometimes on linux the files will download with incorrect capitalisation errors..
(very rare unlikly bug) i know a browser is not the same as the zerok lobby but i did once have an issue such as this that mirrored my browser while i was using the old spring lobby
