You declared $DIRLIST incorrectly
This is how to declare array variable
DIRLIST=(/directory1/dir2/dir3/dir4/ /directory1/dir2/dir3/dir5/ /directory1/dir2/dir3/dir6/ /directory1/dir2/dir3/dir6/ /directory1/dir2/dir3/dir7/)
Then run find command:
find $"${DIRLIST[*]}" | wc -l