Is it this one?
If so, it is being mounted as root.
There are many ways to change this but my recommendation would be to add an entry in /etc/fstab to mount it permanently with the appropriate permissions.
You can use this example from the Arch wiki as a template
/dev/*NTFS-partition* /mnt/windows ntfs-3g uid=username,gid=username,dmask=022,fmask=133 0 0
Replace username with your actual username.