Skyrim: Dibella Sanctum
There's a good reason that the general public is not allowed into the Sanctum at the Markarth Temple of Dibella. The priestesses wear a lot less when they're down there.
Dibella is the goddess of beauty, and its manifestations in art, poetry, craftsmanship, and erotic display. The priestesses provide instruction in the erotic arts, and keep their skills honed in rituals in the Sanctum. While this mod does not add any rituals, it does dress the priestesses appropriately whenever they're in the Sanctum. They cover up when they go upstairs to the main temple.
Before the quest The Heart of Dibella only Senna is in the upper part of the temple, and the other three priestesses are down in the Inner Sanctum. After the quest, they will divide their time between the two parts of the temple, so that two priestesses should be in the Inner Sanctum at any time.
When you rescue Fjotra from the Forsworn, she will get outfits to suit a young Sybil, and change them as the adult priestesses do. Her schedule matches Hamal's, as she is her teacher. As of version 1.2, Hamal's outfit is different from those of the other priestesses, to reflect her rank.
Player robes
There's a set that the player can wear, but unless your character is female, they'll appear as standard monk robes. They're in the Sanctum, on Anwen's left (your right) in this image.