Reverting to Mojave or El Capitan from Sequoia

[laudou]

I have a large collection of .tiff image cds that Sequoia OS cannot read. Therefore I am trying to install either El Capitan of Mojave on a Coffee Lake motherboard. I erased the SSD and formatted it in Apple Extended Journal. I prepared two usb installers using Balena Etcher: one for El Capitan and one for Mojave. The EL Capitan installer returns a "Not supported on this platform" message and does not load, and the Mojave installer boots but stops with some message about Apple APFS.

Am I trying to achieve an impossible task or is there a way to go that I don't know. I believe Mojave is the latest Mac OS version that still supports tiff file reading; am I right?

Thanks for your assistance.

IMG_0482.jpeg.zip

Edited 6 hours ago by laudou
Added screenshot