The name between quotes should be the name of your USB drive. Open up Terminal app and run the following command and press enter.You will need a USB flash drive, at least 8GB in storage space.If you have downloaded it from any other source, place it in the application folder. Download the macOS developer beta from Mac App Store.It is wise to wait for the public beta for a relatively safer experience.Ĭreate a bootable USB drive for macOS Sierra Since macOS Sierra is a developer beta right now, it might be unstable. A bootable USB drive is normally used for a clean install so your Mac data will be formatted.