The SD card URL mentioned R21.4 URLs, so part of those files are for a TK1 and not a TX1 (anything “tegra124” is a TK1, anything “tegra210” is a TX1). Even so, much of that procedure will work with a TX1. I think the trick is that the “driver package” has some of the scripting you are interested in, and the “sample rootfs” has the file system. Unpack the driver package as a regular user, then in the rootfs subdirectory, unpack the sample rootfs as root (use sudo). Once that is in place you will probably have what you are looking for.