@goratnik Are any of the other Chromium-based browsers (Vivaldi, Brave, Edge, Chrome) able to download all the zip files Google drive presents for that huge folder without crashing?

I have a feeling Opera is just crapping out because of all the big downloads where the page and or the download processes are probably running out of RAM. I'm not having an issue download folders in Google drive in general. I don't have any big files like that to test with though.

You don't have to share a link to the folder publicly. But, if you want, you can goto "Menu -> Help -> Report an issue" and file a bug report about it. You can share the link there if you want and mention details and also that you can't get a crash ID. Then, post the bug number hear and maybe someone at Opera can figure it out.