UPDATE
after re installing Affinity Designer plus the trial version still crashed when hitting the print option...checked on mac book no problem...so decided to try another "instance" of the printer...and it worked...test printed a few things including the design/size that crashed ..all printed. Something got corrupted and adding a new version of the printer (Canon Pro9000 mkII) it worked.
If you get the same problem try adding a new version of your printer via system preferences (on Mac) before spending time rebooting/re downloading Affinity.
M
markstejskal got a reaction from Leigh in designer crashes when trying to print on mac