Where does cuda-repo-cross-<identifier>-all.deb come from?

I am trying to set up a cross-compiling environmnt on an EC2 Ubuntu box targeting Xavier at Cuda 10.2.
I tried to follow the instructions at :: which say to install

sudo dpkg -i cuda-repo-cross-<identifier>_all.deb 

but no clue as to where I might get hold of that .deb file, or what <identifier> should be replaced with. I have installed the native package cuda-repo-ubuntu1804-10-2-local-10.2.89-440.33.01_1.0-1_amd64.deb and there are a load of .deb files in /var/cuda-repo-10-2-local-10.2.89-440.33.01, but none of them are that one.

I have looked at Looking for cuda-repo-cross-aarch64-10-2 deb file for jetpack 4.4 DP to compile MXNet python wheel but that doesn’t answer the question.

So it turns out that other thread does sort of answer the question, although it misses out the crucial piece of information that you have to use the SDK Manager, and that you can use the SDK manager without a GUI.