This is where LinkMachine is set to place the link page files. Make sure this directory exists and has all write permissions set to true.
LinkMachine cannot generate the link pages in the directory you've specified as the Location of Link Pages under Site Settings. This may be because the setting is incorrect, the specified directory doesn't exist, or the directory or files within it don't have their write permissions turned on.
First make sure that your Location of Link Pages setting is set correctly. For information about how this should be set, see this page.
Then make sure that the directory you specified in that setting exists on your web server. For example if your Location of Link Pages is set to:
../resources/
...make sure that a directory called "resources" exists in your site's home (root) directory.
Finally, make sure that the write permissions have been turned on for this directory in which your link pages are to be generated, and for all of the files within it that have been generated by LinkMachine. For information about which files and directories should have their write permissions turned on, see this page. For information about how to turn on write permissions, see this page.