Spotify download disappearing when reboot

is the one you call

In order to write on that you need the ntfs-3g package installed. You also have to make sure, that in your Windows installation you disable any Fast Boot and hybernation capabilities, so is not holding any ntfs partition in zombie state.

Also, if you want to automount the Luna partition at boot, you will have to add to fstab something like this:

LABEL=Luna /run/media/soumi/Luna ntfs-3g defaults,noauto,x-systemd.automount,x-systemd.idle-timeout=30min,windows_names,uid=1000,gid=1000,umask=0022,fmask=0022 0 0

considering that soumi is your username on the system too …
Some people recommend using the UUID instead, so it would be

UUID=D8D4C804D4C7E2BC /run/media/soumi/Luna ntfs-3g defaults,noauto,x-systemd.automount,x-systemd.idle-timeout=30min,windows_names,uid=1000,gid=1000,umask=0022,fmask=0022 0 0

Maybe also check How to mount Windows (NTFS) filesystem due to hibernation - Manjaro