John. If you say where this file is posted maybe I or someone else can check it out.

I downloaded the file & think I see the problem. Can't try it as I'm working with the FSX Demo that has no default A321.

If you know how to add repaints to aircraft in FS2002/4 this is no different. Paste the Texture.EZY folder into the A321 folder. Then add the entry below to Aircraft.cfg below the existing ones. I copied it straight out of Aircraft.txt in the download. The title= entry seems to be missing so copy it from one of the original entries but remember to change the Paint number to something different.

[fltsim.XX]  
title=Airbus_A321 easyjet
sim=Airbus_A321
model=""
panel=""
sound=""
texture=EZY
kb_checklists=AirbusA321_check
kb_reference=AirbusA321_ref
atc_id=
atc_airline=easyjet
atc_flight_number=""
ui_manufacturer=Airbus
ui_type=A321
ui_variation=easyjet
ui_typerole=Avion de ligne
ui_createdby=Microsoft Corporation
description=L'Airbus A321 est une version allongée de l'A320, meilleure vente d'Airbus en termes d'avions pour courtes et moyennes distances. L'A321 se caractérise par une surface alaire légèrement plus étendue, un train d'atterrissage plus robuste avec des pneus plus grands et des moteurs à la poussée accrue. Lors de sa mise en service en 1988, l'A321 était à l'avant-garde de l'utilisation du tableau de bord tout écran, premier système de commandes de vol numériques utilisé dans un avion de ligne, et des commandes de manche latéral.

Please tell me if that fixed it.

Did you add that title= entry?
The sim= entry should be the same file prefix as the A321 AIR file.

PS. You could try removing the "" from the model= panel= sound= lines. I'm not convinced they're necessary.

Please note we do not support files from other sites. Please use those site's forums. 

There can be all kinds of crap out there & it's unfair to expect SimV to support outside files. We have a fairly good vetting system & many files do not get posted as they are unfinished or contain errors.

In this case it was your error but generally we do not support non-simv files.