That is the ASICBoost FW from Bitmain. However, if you are not on the other listed firmware:
Antminer-R4-all-201704280718-autofreq-user-Update2UBI-NF.tar.gz
The update will not work. The update listed above changes the file system to UBI or something like that which is necessary for the AB firmware to be compatible as it uses a UBI filesystem but does not contain the necessary files to changeover the existing filesystem.
So if I have a stock R4, the steps would be to first install the Antminer-R4-all-201704280718-autofreq-user-Update2UBI-NF.tar.gz fw,
then the Antminer-R4-xilinx-201811121649-autofreq-user-UBI-NF.tar.gz fw. Is that correct?
Yes, that would be correct! However, be aware that you will the lose the ability from the stock firmware to set your own fan speeds and freq when you upgrade to the UBI filesystem.