BIOS Update Issues; Invalid File

Board model: X579 Phantom Gaming 4s
BIOS version:2.6
CPU: Ryzen 5900x
RAM: G.SKILL Ripjaws V Series 32GB (4 x 8GB)

Notes:

I'm trying to update my bios from 2.6 to 3.2+ to support my new Ryzen 5900x. I've followed the "Instant Flash" instructions on the product page (https://www.asrock.com/mb/AMD/X570%20phantom%20Gaming%204/index.asp#BIOS) and there are a couple issues I'm seeing:

1. Initially I tried this by downloading 4.0 and extracting it to a FAT32 USB stick. I then went to Tools in the BIOS and clicked the update button and got the message Invalid File.

2. I then thought maybe 4.0 was the wrong version and downloaded 3.2 and extracted to my USB drive. When I went back to the BIOS Tools "Instant Flash", the only option available was for 4.0, which I had deleted.

3. Per a recommendation from a friend, I removed my SSD card and went back to the BIOS>Tools>Instant Flash and this time there was a "No image file detected", despite me having my USB stick inserted with 3.2

4. I've tried multiple USB ports and am still unable to update my BIOS, with the Tool only showing 4.0 and then giving me the "Invalid File" error.

Can anyone help me understand what's happening and how to fix this? It seems like the BIOS is only reading my SSD card, though I'm not sure why.

Thanks in advance!

i was going to say
are you sure your trying the correct boards bios files