Installer is 53MB - that’s not going to turn into 7GB. It runs, takes a few minutes updating itself (pausing at 81% for a few minutes), then gives us this “Subscribe” button where there should be a Launch button (or Install button?). If there is something else we were supposed to download, it’s not there.
I ended up building source code - turns out even if launcher thinks we’re not subscribed it still lets us download from Marketplace, so ultimately we can cobble it all together manually.