Translation:We are looking for someone with a vivid imagination.
You can have a vivid imagination, which means you are generally imaginative, you have an imaginative mind.
You can also have a fantasy, a dream about something you might want to do, like going to the moon.
And you can have a vivid dream, but I don't think that would fit here.
But I don't think you can have a vivid fantasy.
Well, I don't remember what made me accept 'fantasy', so I guess I will listen to MacMillan and delete it.
Using the word "fantasy" has a sexual connotation to it. I would not vote this one. I can't agree Jellei. It will sound odd and it will definitely make people think 'sex'. Then again... maybe under the right circumstances that what you want :)