Your Canon R6 requires Adobe Camera Raw 12.4. Elements 2019 does not support that version. There is a possible workaround that you can find here. However, I suspect that it will not work with Elements 2019. I have tried the workaround using ACR 13, but that will not work in Elements 2021. Because there have been major changes in the ACR since Elements 2019, I doubt whether ACR 12.4 will work with Elements 2019. (It does work with Elements 2021.) Please report back if it works for you.
Otherwise, the standard solution is to use the free Adobe DNG converter which will batch convert your raw files to the DNG format which will work in Elements 2019.
Sorry if I was unclear. ACR 12.4 does work with Elements 2021, using the workaround I posted. You can check it out for yourself by downloading the free trial of 2021. If you decide to go this route, make sure you download ACR 12.4 and not any later version (currently 13.0).