Measure your desired mounting location on your wall.
A 9ft - 10ft height is recommended
Use a Magnetic level to hold your top wall bracket in place and level at the desired height and location. Mark your holes.
Predrill 2 of your anchor holes if using concrete anchors. Place your bracket back on the wall and secure 2 anchors. Pilot the next 2 and install anchors while the bracket is in place so you’re certain these are in the correct location. Ensure a snug and secure hold on your wall.
Pre Assemble your Extension arm and Leg support together and in line.
Using 2 ladders / or similar, have 1 person hold your assembled Extension in place and against the wall. Feed your bolts though and secure with the washer, then locknut. Use an impact driver / socket / 3/4in wrench to snug and secure your anchors.
Pilot and Anchor in your last two wall bolts in the leg support. Ensure your extension is level and the weight of the extension is supported with the angle leg support.