The ROM is a customised version for the FAST machines. RISCOSbits strongly advises you against using standard ROM builds as they do not contain the 'extras' needed for the machine. The software is supplied as a zip which can be downloaded from a secure protected area - details are in your user guide along with the password.
This version is all about SATA disk support (a major attraction of the system). This ROM adds support for optical drives and 4Kn/512e drives over 256GB. So if you are looking to use big capacity drives with RISC OS (which currently have to be supplied and formatted by RISCOSbits) this is an exciting release. There is no change to the generic RISC OS version the software is running on (stil RISC OS 5.29 from February 2023).
There is also a reversion of Menu back from 0.41 to 0.40 due to a bug found which stopped some menu items appearing.
The zip itself contains the ROM and a readme file. It would be nice to have an installer App in the future, but installation is pretty straight-forward. Replace the ROM in the SDFS copy of !Boot.Loader with the new one - I would make a backup of the old copy first just in case - and reboot. By default you will not be able to see FASTSD drive as it is hidden. In your Apps folder, you will find !SDCtrl - running this will make the drive visible or invisible. Then reboot your machine.
Personally, large optical drives are not a big RISC OS requirement for me, but it is very nice to see RISCOSbits making regaular updates to extend the machine and make use of the SATA hardware support. Looking forward to seeing what is in the next release...