I don’t understand “collaborator” here.
Hungary openly fought on their side —the decision was made for the ENTIRE country.
It seems the author is imposing the WW2 history of Vichy France on Hungary.
The only prominent Hungarian collaborator I know of is George Soros, and that moniker can be imposed on him only insofar as his role vis-a-vis Jews in Hungary is concerned:
He betrayed them.
Hungarian Hussars (light cavalry) of the Austro-Hungarian army around 1914 I think.
https://s-media-cache-ak0.pinimg.com/736x/fc/d3/f5/fcd3f5c2b1ae912c0423055b2c1f5212.jpg
Spanish Regiment of Pavia - 1909
https://s-media-cache-ak0.pinimg.com/236x/6b/48/1a/6b481a6374c4ab2f2a0da8e669fa32bb.jpg
King Edward VII as Colonel of Hussar Regiment 12 (The Austrian “King and Emperor” regiment - “kaiserlich und königlich”)