Mine came with the flange and I never measured...I'm not 100% certain what the diameter or bolt pattern are. Depending on how big a hurry you're in I'll have it down in a month or so to inspect it and I can measure then.
For what it's worth, though...I don't know who prices end up being in Germany, but in the States this turbine cost me $300usd. For $400usd I can buy an iSta Breeze i1500 that does three times the work. Just something you might look into.
The eBay store and the vevor store from aliexpress say that it came without the flange

425€ the ista breeze i1500
And 260€ the vevor ne-700m4

at this time starting with wind energy and doesn't will pay too much, because the German law doesn't like own wind energy in garden... So it's hart to get it licensed.
I built it into my garden and wait if anyone will say anything

So what's the durability of the ne-700m4 any Experience with it..?