Stand the marquee on the lawn before the deposit
Six metres by nine sounds fine on the phone. On the actual lawn, with the washing line and the apple tree, it is a different conversation.
Choose a size
Drag to walk round it
Opens your camera. Point at the lawn and walk back.
Once it appears: one finger drags it, two fingers turn it. It does not need a clear floor. Drop it where it fits and judge the size against what is already there.
Will it fit, and how many will it seat?
You need guy room all round, and the ground has to take stakes or ballast. Then you can count chairs.
Let them scan it and hold their own phone up
The camera view only works on a phone. Point the code at their camera, and this page opens on their handset. That is the moment the idea sells itself.
Capacities are typical for round tables of eight with a service gangway, or for a standing reception. Guy line allowances vary with the frame system; some clear span frames need less. Ballast weights are indicative and should be calculated for the expected wind loading. Heating, lighting and power are separate considerations.