Make sure you installed the Treetagger, a POS tagger. For research you can use it for free. Please visit https://www.cis.uni-muenchen.de/~schmid/tools/TreeTagger/ for more information.
To get the DIAsDEM Workbench working check out the code, make sure you add all the libraries from the lib folder into your classpath (these libraries are not available in the Maven Main Repository).
Under IntelliJ run the main class with the following parameter (without mentioning DIAsDEM.plugins)
org.hypknowsys.diasdem.client.gui.DIAsDEMgui.java /path/to/your/DIAsDEM.plugins
For test data please clone DIAsDEM.workbench21 in this Github project.