1. Go to Real World Scale
Open model in real world scale (see step by step instructions here)
2. Set opacity to see-through
Lower the opacity to see both 3D-model and built environment together
3. Roughly align model
At this stage, the model scale is locked to real world-scale. Move it by dragging with one finger and rotate with a pinching movement.
Move around to see alignment from different angles
5. Fine-tune (if necessary)
Fine-tune alignment if necessary when you move around
BIM there, done that!