GMC 2018 Acadia Denali Owner's Manual page 101

100 Seats and Restraints
If the child restraint or vehicle seat
position does not have the LATCH
system, you will be using the seat
belt to secure the child restraint. Be
sure to follow the instructions that
came with the child restraint.
If more than one child restraint
needs to be installed in the rear
seat, be sure to read Where to Put
the Restraint 0 91.
1. Put the child restraint on
the seat.
2. Pick up the latch plate, and run
the lap and shoulder portions
of the vehicle's seat belt
through or around the restraint.
The child restraint instructions
will show you how.
3. Push the latch plate into the
buckle until it clicks.
Position the release button on
the buckle, away from the child
restraint system, so that the
seat belt could be quickly
unbuckled if necessary.
4. Pull the shoulder belt all the
way out of the retractor to set
the lock. When the retractor
lock is set, the belt can be
tightened but not pulled out of
the retractor.