Hey everyone,
This sounds like the “Failed - Network Error” issue we’ve seen affect some players. If you haven’t done so yet, please check out the pinned forum post that covers a lot of what can help here: [Main Thread] "Failed - Network Error" with Battle.net Set-up file
I like calling out one step which is to try an alternative connection. One cause is corrupted data either in the network or cached by the ISP, so trying an alternative like a hotspot or mobile tether often gets around this. If this works, then switching back to your normal connection to install is usually fine.