Its in the github page. Click on the "Lenovo Storage Host Bus Adapter HBA Windows Firmware" link. Download the 25.37MB "payload file" script . If it asks for a serial, click "cancel" and click download again. Create a folder to hold the firmware and bios files. Open the script you just downloaded and click "extract". Choose the firmware folder you created and the files should be in there. This helped me create a UEFI Shell boot device https://github.com/KilianKegel/HowTo-create-a-UEFI-Shell-Boot-Drive?tab=readme-ov-file