Sorry for the misreading your description, I guess I am still missing being able to see the broader picture for your situation.
Following on from Disable “Auto download over Wi-Fi” being missing, I see no mention of unlocking. I wonder if we are actually looking for a very simple explanation!
Please can you send a photo of you Odin mode, or Download mode screen. It will be hard to capture the smallest print, perfection not required!.
(I had proposed the reboot button only as an alternative to the “Keep read only” if it were missing.)
Old threads, may contain insights Installing /e/ OS on Samsung S9+ - need step by step help Easy installer - "continue" button not visible