CITROËN DS4 Owner's Handbook Manual page 154

Storage drawers
Located under each front seat, except for the driver's seat on versions with electric seat.
On the passenger's side, the drawer holds the vehicle handbook pack.
Opening
Raise the front of the drawer and pull it open.
Do not place heavy objects in the
drawer.
Removal
Avoid removing the drawer completely, as
refitting it is not easy.
Open the drawer fully.
Pull the drawer upwards to disengage it.
Refitting
However, if it has been completely removed, to
refit it:
use the torch to illuminate the area under
the seat,
engage the drawer in its runners,
lift the retaining tongues and slide the
drawer under these tongues,
at the end of its travel, press down on the
drawer to engage it.