I just installed P3D V5 after leaving FSX for XPlane 11 some years ago just got the textures working for this lovely bird using the old dusty FSX installer which I installed to C:\Program Files (x86)\MyProduct
Probably easier ways exist but simply I copied all the textures for example from these 5 directories (all the .dds files) and pasted them into (in my case) D:\Lockheed Martin\Prepar3D v5\SimObjects\Airplanes\Classics_Hangar_Bf108B\texture.DEBFW (and did the same technique for the others)
From D:\Lockheed Martin\Prepar3D v5\SimObjects\Airplanes\Classics_Hangar_Bf108B\texture.DEBFW - the texture.cfg
fallback.1=\4096
fallback.2=\texture
fallback.3=\texture.canopy_silver_4096
fallback.4=\texture.cockpit_brown
fallback.5=\texture.panel_historic
In my case this fallback stuff did not work because I did this in each texture.cfg to no avail. Anyhow the above worked for me 100%.
Was happy with this result so reporting. Doing sound next.