Translation:I will have made dinner ready when you arrive.
I agree, the translation is clunky.
I think in English I would say instead, "Dinner will be ready by the time/when you arrive" or if I really wanted to stress that it's me who is making the dinner, maybe "I will have dinner ready by the time/when you arrive" or even "I will have made dinner by the time you arrive" (but both sound weird).
Danglish! Madness! The English isn't English and the Danish doesn't sound like Danish to me but if that's why they want, give it to them. I feel sorry for those of you who are not native English speakers and who might actually be fooled into believing that the supposedly correct English versions provided here are actually English. As we say in English, "take it with a pinch of salt". But please don't use the English that they are displaying here. You are better than that.
I wrote in 1:1 translation" I have the dinner ready when you arrive" and it was not accepted. In the answer above I would have written " Jeg vil have lavet..." Am I wrong and pls where? Otherwise I am with you with "Dinner will be ready when you arrive - Aftensmad vil være klår når I ankommer". What do you think??