# The Lord has covered the daughter of Zion under the cloud of his anger

This speaks of the Lord's anger as if it were a dark cloud. 

# the daughter of Zion

This is a poetic name for the city of Jerusalem. Translate it as you did in Lamentations 1:6.

# He has thrown the splendor of Israel down from heaven to earth

"Jerusalem, the splendor of Israel, has lost all favor with the Lord"

# He has not remembered his footstool

"He disregarded Jerusalem as his footstool" 

# on the day of his anger

"at the time when he displayed his anger"