There are various gui applications to create cd and DVD disks. For example the xfce project has the xfburn program, and I am sure the Gnome project has one as well.
That error seems to be because sudo was not used.
bs=512 is the default and copying in that way works much faster with a larger block size such as 32M, 64M, or even 128M.
I’m going to spam my own page on this, which deals with it from command line. Though some of it is outdated, the basics are still applicable. https://srobb.net/dvds.html