Print on 4x6 index card

I have a 4x6 recipe card that was created with LibreOffice writer on Win 10. It is the odt format. It will print fine here using a Canon MF650C series laser.
Well, time marches on and now I have a MacBook with LO. And I just can’t seem to make it print out on the 4x6. It looks fine in LO and it looks fine in the Print Preview. There doesn’t appear to be an option to select 4x6 paper in the Printer Setup → Printer Options panels.
Moving on to the Print dialog, I created a 4x6 Preset and selected my 4x6 index as the Default paper size in the Mac Printers and Scanners settings. Even the picture of my 4x6 card looks OK in the Print dialog.
But when I hit Print all I get is a little bit of text on my 4x6 card and an error message on the printer “Paper Settings and Loaded Size Mismatch”
My, oh my, what could be wrong?

I don’t have a Canon, but for my Epson printer, I have to set the paper-size also at the printer itself. I’m usually asked when closing the paper-tray to confirm the type of the paper (or change). If it doesn’t match the job-data, it will not print…

Thanks for the reply Wanderer,
Yeh, my Canon has a “Register Paper” feature on the printer. There you tell it to use either the multi-purpose tray or the paper drawer. And you tell it the dimensions of the paper you are using and give it a name. And I’m assuming that this info is passed to the computer when asked to print.

I did a little more toying with my MacBook, LO and Apple Pages.
In LO I saved my document as a .docx. OK, I understand some formatting may be lost when saving as docx. Then I opened the docx in Apple Pages. Sure enough I had to reformat sections of the document to make it fit properly on the 4x6 layout. In Pages menu I went to File → Page Setup and there I was able to select…
Format for → Canon printer
Paper size → 4x6 index (my registered paper size)
Orientation → Landscape
Scaling 100%
And to my surprise it printed out perfectly.

So the question is, where in LO do I get to select my papersize that is “registered” for the Canon printer? It does not seem to exist in LO’s Format → Page Style dialog box. ???