The integrity check declares two files as broken:
setup_baldurs_gate_3_release_-_v4.1.1.6072089_-_patch_patch7_hotfix3_(64bit)_(77035)-21.bin
and
setup_baldurs_gate_3_release_-_v4.1.1.6072089_-_patch_patch7_hotfix3_(64bit)_(77035)-28.bin

I have downloaded them three times already to no avail. Cannot install the game.

What for? There is nothing to see, both look exactly like the other 31 files do. I'm not missing a file, I didn't download files twice. The installer tells me those files are broken and then I can only quit the installation.

Because that is what I wanted in order to help. Never mind.

I appreciate your help and meant no offense, but I just don't see the point. I have been dealing with this problem for a quite a while now, several new downloads with different computers to different HDs. Always leading to the same result. All I wanted know is whether other people have had this problem before I open a ticket.

They probably have, but you've done a pretty good job of showing you're going to respond in a hostile way to any attempt at helping, so I doubt anyone else is going to be super eager to try.

The fact that you didn't notice something odd in explorer doesn't mean that someone else wouldn't. Unless you're asserting that your diagnostic skills are perfect, in which case why bother asking for help?

You may as well just open that ticket.

one thing it shows us is you are talking about German files not the default which is English so thats new infomation we didn't have from your post

another thing it would show us is the file size because server can desync and if the file isn't 4G in size then shoowing us an image would be a good way to spot that

Just as a small note, there are no "German" files - all BG3 offline files are "English". Gog's launcher reads the Windows locale and then selects the appropriate language (which is "German" in the pic above), I assume this should have nothing to do with the actual problem. But anyway, I wanted to install the game on a Win laptop anyway, if desired I can post the result here later.

if you don't select English there should be an extra folder with the new text file so Spanish or German etc

i checked again here [downunder] the Gog server is giving me correct files but if you still get corupt then first look that they are all 4G in size ... only the first and last should be of a different size

good luck

Sorry I'm late, but: mom's spaghetti first - broken files last, right?! ;) What I actually wanted to say, ussnorway, was that you only get the English files when downloading, “English” is the only option. The languages of the game/launcher are set when you actually start the installation. So all the files we download should be the same, correct? Just in case I have installed both language versions of BG3 (E/G; incl. integrity checks) - and everything was fine, no corrupt files (server name was "gog-cdn-fastly.gog.com"; dunno if they have more than one). The case remains mysterious.