Ask the Internet Braintrust

Anyone happen to know how you get an iPodTouch 8 to download all of your existing music from your computer onto the iPodTouch 8, so that the iPod can play it without needing a wireless connection? With my eight-year old and much-mourned iPod, "sync" did this. It's not clear what effect if any syncing the iPodTouch8 with iTunes on my computer had, but apparently "download music" is not among the effects.

(And I know I should ask Google, but I am at the point of wanting to turn the box upside down and read the answer instead of trying to solve the puzzle. -_-)