Test-fit a fencing panel on an installed corner chain-link fence post. Position the fencing panel at the desired height. Mark the post where the lower edges of the horizontal rails cross the post. Remove the fence panel. Tie a string to the post at the level of the top mark. Extend the string to the adjacent corner post. Hang a line level on the string, then tie the free end of the string to the second corner post. Mark each post between where the horizontal string crosses them. Repeat to mark the positions of the lower rails on the metal posts.
Place one post adapter for each rail on each steel post. Rotate the adapter so its support shelf is positioned to hold the fence rail in the desired position. Align the shelf to the mark on the post. Tighten the adapter onto the post by turning the bolt on the clamp with a socket wrench. Repeat to install the remaining clamps on the fence posts.
Lift the fence panel, then position its rails on the shelves of the installed adapters. Ask an assistant to stand on the front-side of the fence to hold the panel securely in place as you screw the adapters to the fence panels. Pass the tip of a screw through the back of the shelf on the adapter. As your assistant holds the fence firmly against the adapter, drive the screw into the rail of the fence panel. Repeat to screw the fence rails to the installed adapters.