Apparently you’re supposed to play 3 battles on the Classic server.
The style and emblems should be awarded after the event.
Note: take this info with a grain of salt, since WG did not mention anywhere anything about how you can earn them. I’ve asked my WG contacts and they confirmed it.
https://na-wotp.wgcdn.co/dcont/fb/image/01_wot_classic_unique_style_for_the_maus_1920x1200_s.jpg