It’s actually very easy to burn Ubuntu Desktop ISO to a USB stick when all you have is a MacBook: all the tools are already available, all you need is to open the terminal and start cranking. First, plug the USB stick to your MacBook. Then, start Terminal and type in:

% diskutil list external
/dev/disk4 (external, physical): etc etc

/dev/disk4 is your USB stick. Now, unmount it and copy the ISO onto it:

% diskutil unmountDisk /dev/disk4
% sudo dd if=ubuntu-25.04-desktop-amd64.iso of=/dev/disk4 bs=1m status=progress

Eject the drive after the copy is successful:

% diskutil eject /dev/disk4

Done - the ISO is burned onto your USB stick and can be booted from.