Building Kernel Drivers for old kernels

[Linux for blind general discussion]

OS, arch linux.
I have this PCI card in my box:
03:00.0 RAID bus controller: HighPoint Technologies, Inc. RocketRAID 644 4 Port SATA-III Controller (eSATA) (rev 01)
04:00.0 RAID bus controller: HighPoint Technologies, Inc. RocketRAID 644 4 Port SATA-III Controller (eSATA) (rev 01)
Incidentally, what does it mean when it appears twice like that?
Anyway, when I plugged in all my drives, only one disk out of the twelve I have connected to the card shows up. As you can imagine, this is not good for my raid lol.
I went looking and I found a linux driver on the highpoint website. However, it is for 2.x kernels. My kernel is
Linux trainserve 5.7.7-arch1-1 #1 SMP PREEMPT Wed, 01 Jul 2020 14:53:16 +0000 x86_64 GNU/Linux
I don't think it is going to build a module for a kernel years newer than it is designed for.
What can I do here? Would this require a complete re write of drivers? Should I junk this card and try to find something newer?