[Belafon]

Nagaji - Naga Aspirant Druid Archetype

Aspirant’s Bond (Ex): A naga aspirant gains a spiritual connection to the serpentine deities worshiped by the nagas. At 1st level, and each time she gains a druid level, she may add one of the following spells to her druid spell list.
0—acid splash, bleed, daze, mage hand, open/close, ray of frost; 1st—charm person, divine favor, expeditious retreat, mage armor, magic missile, ray of enfeeblement, shield, shield of faith, silent image, true strike; 2nd—acid arrow, detect thoughts, invisibility, mirror image, scorching ray, see invisibility; 3rd— dispel magic, displacement, fireball, lightning bolt, suggestion; 4th—divine power, greater invisibility.
This ability replaces spontaneous casting.

Hero Lab is only allowing you to choose spells that you are of a high enough level to cast (in other words you can't choose divine power at 1st level). As the ability adds the spell to the druid spell list, you should be able to select any spell at any level. As an example you may want to add fireball to your spell list at level 4 so you can use a wand of fireball without a UMD check even though you cannot prepare the spell yet.