If you are experiencing issues when trying to open PDF files which were created in MyConstruct the likely cause is your PDF viewing software.
The easiest free option that is recommended is to install Adobe Acrobat reader:
Otherwise Google Chrome is very good at handling PDF's by default and should also be considered
Another possible issue with viewing PDF files can be the chosen default application which is opening the PDF files on your computer. In windows PC's simple right-click the PDF file and choose "Open with" and change to the correct PDF application.
For Mac please consult the help articles on the Apple website, example: