thank you for your feedback. Did you install Modelur 0.5.6-r03 over some previous version?
Regarding the your problem, please do the following:
latest release of Modelur.
2. Delete /Modelur folder and modelur.rb file from C:/Users/<username>/AppData/Roaming/SketchUp/SketchUp <version>/SketchUp/Plugins/
3. Delete /Modelur folder from C:/Users/<username>/AppData/ (if it exists)
4. Install the new version of Modelur (0.5.6-r03) and license it using your license key.
As for the Mixed-use buildings, Modelur is limited to creating only one instance in trial mode. Are you not able to create even single one?