SVN error note "Failed to add directory 'trunk/build': an unversioned directory of the same name already exists" means that your locally ignored directory has been added under version control. Maybe someone else did it, maybe you did it initially before deciding to ignore.
The fix is to remove those directories from version control. There's nothing you can do locally to fix it, you have to access the main, common, shared repository in network. Remove the directories, do refresh and updates.
Reminder how to ignore directories locally: go to folder (trunk), which contains directory (build) you want to ignore. Do command line "svn propedit svn:ignore" and make sure your list contains all the directories to be ignored.
If that command doesn't work (bash), define your editor as "export EDITOR=emacs" or whatever is your favorite editor. Control-x Control-c exits from emacs, in case you get stuck.
svn status, svn update and svn cleanup might help, too. Remember to read SVN manual BEFORE using any of those commands. You have been warned, all caused problems are own own responsibility.