Heyho!

I recently tried to install an OS on an Pentium 2 and ran into various issues:

Dos Boot Disk:
I copied the Dos Installation images from https://winworldpc.com/product/ms-dos/622 onto 3 3,5 Disks via "diskwrite". However, they did not work as boot disks.
I also tried an old boot disk we still had from 96, but that worked neither.
"Boot Failure
Insert BOOT diskette in A"
I also talked to my brother and he ran into the same issue a while ago.
Is there a specific reason I didnt see here?

Partitioning/formating a 16 GB SDHC:
I had multiple issues in partioning it. Because the DOS Boot disk wasn't working, I first just started the Win 98 installation and expected to be able to set partitions and whatnot. Maybe that's what I remembered from Windows XP, don't know. In any case, the Win 98 just scanned my drive and found various issues which it "corrected". Well..it failed anyways before starting the actual installation.

I then booted with CD support with the help of the Win 98 SE CD and used fdisk.
From what I remember DOS can only handle 8 GB and each partition should be 2 GB max.
So I set a primary partition with 2 GB, and a secondary with...why did it offer 13 GB? Because of DOS 7.0?
So...well, I used the 13 GB and made several logical drives with 2GB and one with the rest.

Now I was curious about what DOS has to say about that and experienced the issues with the dos Boot disk and installation I mentioned before.
Then I resigned and just went ahead trying the windows 98 SE install. Attempt now went through to copying files which failed because it couldn't write files to the disk.
I just tried again and that time it worked. However Windows completely ignored the partitions I set before and just made one big one with the main drive now.

So yeah...I'd like to understand what happened here.
Is there anything special about DOS Boot disks?
What is the proper way to use 16 GB SD cards for DOS? If possible I'd actually like to use them on 6.22 (and not on Windows 98 / DOS 7.0) Which steps do I need to take here to make it work?
I don't need 16 GB capacity, 8 GB are perfectly fine (16 GB were just the only ones I could buy)