MacOS – How to change the location of the Music folder on macOS

Purpose of this folder:

When iTunes synchronizes photos to your iPod, it actually converts and resizes them into 16-bit bitmaps in resolutions appropriate for the iPod. It stores the converted photos in the iPod Photo Cache folder before transferring them to the iPod. This basically allows iTunes to quickly add/remove photos from your iPod without having to reconvert them every time. If you remove a photo album/folder from your iPod (by unchecking the box in iTunes preferences), it will still leave the pictures in the cache in case you want to add them again in the future.

Possible workaround:

Move the iPod Photo Cache folder to the location of your choice, and make an alias (shortcut) to the folder in its new location. Place the alias in the folder where the iPod Photo Cache originally was (usually in the Pictures folder) and make sure the alias is named "iPod Photo Cache". When iTunes looks for the iPod Photo Cache folder in the Pictures folder, it will instead find the alias, directing it to the new location.

You didn't specify the OS of the computer but on Windows that would be a junction point.

On windows you can't redirect only these two folders (on OS X and Linux you can) - BUT you can move the whole "iTunes Media" folder to D: then all updates will go there.

In iTunes "Edit > Preferences...->Advanced Section" you can change the location of the media folder - the new folder on D: doesn't need to have the name "iTunes Media", it just need to have the same structure as it had on C:.