I would like to erase the existing operating system and install Ubuntu on my Macbook6.1.
I am following this tutorial to create a bootable USB device. But my USB stick does not appear as bootable device in Apple's 'Startup Manager' on step 7.
I set the format to MS-DOS (FAT) and the scheme to GUID Partition Map when preparing my USB stick on step 3.
I tried with the 18.04.1 and the 12.04.5 releases, and I tried using Etcher (as in the tutorial) and UNetbootin to install the disk image on my USB.
I am using a mid-2014 Macbook Pro to prepare the USB stick.