can anyone tell how to backup material library on usb drive on MacBook?
Search on Mac for a file with “.clb” ending, typically in the LightBurn library, from there you can copy it normally to a USB stick.
You can also use the import/export option or save everything (all settings) in a “bundle”
I can’t on a MAC, but I do know it is a ???.CLB file, and may be in a Libraries folder (at least that is where mine is).
Or save directly in the Material Library window: