Xcode 11.1 "There is not enough disk space available to install the product"

The App Store shows me that I need an update: Xcode 11.1 is here.

When I try to install it, a box appears with the following text:

"There is not enough disk space available to install the product"

I have 20GB free space. I would hope that should be enough...

So I went to Google and found this: https://stackoverflow.com/questions/53432700/xcode-on-mac-app-store-cant-install-show-disk-space-not-enough.

It refers to this: https://developer.apple.com/download/more/

So I tried to downoad Xcode from apple directly (I got a .xip file with Xcode in it (7,68 GB!).

And I tried unzipping it. I got the same message: too little space.

OK

So I tried hooking up my external harddrive to my laptop, and putting the xip file on there and unzipping it. I have 1,73 TB (!!!) free diskspace on that external harddrive. You would say that would work, right?

Nope.

Still got the same message. "The archive "Xcode_11.1.xip can't be expanded because the selected volume doesn't have enough free space."

What the heck is this? Is this version of Xcode corrupted?

Did anyone else experience the same issue and perhaps have another solution?