Remove boot trim
First, remove the boot floor. the arrow indicated where the amplifier will go.
Then, remove the plastic cover from the rear side of the boot. It's held in place by two torx screws and 4 plastic clips. Always use plastic tools to remove these and other clips to avoid damage to the plastic parts.
Now, remove covers from the sides. The right one is held in place by 4 black clips...
... and the left one by 3 clips.
Right cover removed.
Left cover removed.