50mm should work perfectly fine, an 85mm might be a bit too long assuming the photographer was on the same (level) ground and of average height. Judging by the example photo you provided it appears that the angle of view is relatively close, with a small aperture (maybe f/8-f/16 at 50mm) when looking at the bokeh. The size of the camera sensor would affect this, so I'm comparing to full frame camera. If a longer lens was used, the person would likely need to stand on something otherwise the horizon would start to come into view, as the perspective is slightly downward in the example.
You could also use a wider lens (e.g., 35mm) with larger apertures if you don't have enough room to move back for the desired composition. Just be aware that lens distortion might become a factor if you have straight lines anywhere, or subjects near the edges of the frame; most wide angle lenses tend to be softer toward the edges.
With regard to the lighting, it looks like it was an overcast day as there are no strong highlights on the people. There are also no discernible shadows on the ground except for under the sofa, and the plants do not appear to have strong contrast. You could use some sort of diffuse (a bed sheet held overhead or to the side), but it might look weird with the rest of the scene showing stronger shadows. The cloud-diffused sun appears to be above and slightly behind the subjects. There was probably some reflected lighting from in front and to the side of them as well as they are very evenly lit.