Hi, I made a TM backup of my old macbook pro before it stopped working. It was running on El Capitan with many important apps. If I buy a 2018 Macbook Air (running, presumably, Mojave) can I just start the new Air up, press Cmd-R and restore from old backup? Will my Macbook Air then be running on El Capitan with all my previous apps and files intact? Or is this process fraught with difficulties?