I just noticed LineageOS seems to offer some slightly fuller explanations Install LineageOS on beyond1lte | LineageOS Wiki. I am not a Windows user, so only read the Linux steps when reviewing the docs, but perhaps Odin is not equipped to deal with R? I didn’t know - but an Odin method found in # post 20.
When searching for firmware you need the model number in the format SM-G973F … is that your exact model?
Did you already search the 4 options at Know your hardware - Samsung Sammobile downloads can be very slow: https://www.sammobile.com/samsung/galaxy-s10/firmware/