The disk format should be Mac OS X extension (Journaled).Use “Disk Utility” to erase the above-mentioned media or partitions, the requirements are as follows.It is recommended to use USB external storage to avoid erasing the entire internal disk for major version updates. Use the system “Disk Utility” to create a new partition, which is suitable for experienced users.

USB Portable Hard Drive: such as USB SSD portable hard disk is better.U Disk: Catalina and above versions require a U disk with a capacity of 16G and above, and other versions require a U disk with a capacity of 8G.You can use one of the following three media, U-Disk, USB Portable Hard Drive, Create A New Partition.Click the package in PKG format will automatically install it to the “Applications” folder according to the prompts.Packages in DMG or ISO format need to be opened and dragged to the “Applications” folder.Apps downloaded in the Mac App Store will be automatically saved in the “Applications” folder.Make sure that the downloaded installation package is in the “Applications” folder.Choose the corresponding macOS system version according to your computer model.

How to make a usb drive bootable on mac