okok breaking it down region by region...

diyu

u'du - this is where the peasant class of the Diyese live, so their fashion tends to be very simple and plain in fabric/color. a lot of the people here make their own clothes too! the style tends to vary/blend between traditional Chinese peasant clothing (another example) and just casual wear.
marianne/maa'lan - there's a lot of mixed Yangwai-Aesht'fritun living here. the clothing tends to be more of a blend between Chinese styled clothing and Himalayan/Tibetan clothing.
y'ao - the population here tends to wear clothing inspired by Japanese street fashion. due to their relation wiht y'ohe, they are also inspired by Dvarian clothing, so will also wear flowier fabrics.
injung - this is where a lot of nobles live! in their day to day lives, nobles tend to wear a variety of fashion styles. oftentimes, the different noble houses will adapt a specific fashion style/trend to create greater cohesivity among its members. in their day to day, they tend to wear trendy, modern clothing (see jennie and arya's pinterest boards), but they will wear Very Expensive Brands to parties/events.
engfu - [redacted]

venere

lume - since it's close to the beach, Venerians here tend to wear a lot of beach-wear/summer-wear. the general fashion also takes inspiration from French fashion/styles.
arisii - this is basically the Venerian equivalent of U'du. Most of the population lives here. The fashion tends to be on the simpler side with more homemade clothes than Lume (although considerably less than U'du). the style varies/blends Indian fashion and casual wear. The eastern Arisii will also see outfits inspired by Filipino fashion.
montfeu - the sister of marianne, montfeu fashion consists of a lot of Himalayan/Tibetan clothing.

dvar

as Dvar has long since been abandoned, each region doesn't have their specific style of clothing anymore. however, Dvarians (and ex-Dvarians) ((aka just Meeren)) tend to like flowier fabrics that mimic the water in how they move. pretty much ALL of their fabrics are a combination of linen and tulle (they LOVE tulle)

kumo

oma - as it is the financial district, many will wear a suit or other professional garment when out in public (although usually without ties. it's more business casual.) the suits tend to be high class brands
tari - as it is very cold here, furs are very common! big furry coats. the style of the fur coats (and hats!) tend to be Russian. for some reason, those living in Tari love hats...
rho - those attending schools in Rho adhere to the schools' specific uniforms. those that live in Rho wear very classy and simple outfits. think upper east side of New York.
aten - the clothing here is inspired by a blend of modern clothing with a Grecian twist. those living in Aten like having flowy fabrics that are comfortable and easy to move around in.

edan

terres - anything goes! this is where every culture comes together as the political hub of the world, so you'll see ANYTHING here.
massu - the fashion here tends to involve a combination of modern clothing and Tang dynasty Chinese clothing.
azrelle - Azrelle is a popular tourism destination, so you'll see a mix of all kinds of fashion here. for Azrelle natives, though, wear loose and casual clothing with a lot of cotton, silk, and lace
khamae - due to the cold, the people here wear many layers of clothing. the fashion here tends to be inspired by Alaskan Native clothing.
shivra - as an agricultural area, a lot of those in Shivra wear clothing they're not afraid to get a little dirt on. for the temple structures, those for the Earth deity will dress in long robes while those for the Sea deity will wear Dvarian clothes embroidered with gold and silver
essandre - Essandre has the largest Demon population in Edan, so a lot of the clothing is inspired by Diyese and Venerian fashion. additionally, for non-Demons living in Essandre, their clothing tends to be like old English peasants blended with modern clothing. 

(and of course, because globalization yadda yadda, none of these are concrete! everyone still wears what they want to wear the most... but these are just what's most common for each region :])