It is right outside the Acropolis Metro Station on 2-4 Makrigianni pedestrian Street. The spot is also the side entrance to the Acropolis Museum.
Right across the Crescendo cafe
Acropolis Metro Station, Athens 117 42
https://maps.app.goo.gl/bQYmn8AScDvkXoPZ6
https://maps.app.goo.gl/gURj7fZZPhMebPDn8