HPE ProLiant DL380 Gen11 User Manual page 120

3. Connect the CMA hinged tabs and retention bracket to the server rails:
a. Insert the inner tab into the slide rail (callout 1).
b. Insert the outer tab into the mounting rail (callout 2).
c. Insert the retention bracket into the opposite mounting rail (callout 3).
There will be an audible click to indicate that the tabs and bracket are locked into place.
HPE ProLiant DL380 Gen11 Server User Guide 120