Hi,
We do not actually write or maintain the code for these extensions - we simply host them in the BApp Store for the benefit of our users. From looking into this particular extension, there appears to be a general issue with using it with Burp Community edition, as noted here (other users are experiencing the same issue as you):
https://github.com/GovTech-CSG/Autowasp/issues/7I believe that the author is going to reach out to us so that we can see if we can resolve this particular issue with them.
On a general note, the version of Burp that you are running is very old (nearly 5 years old, in fact). Have you considered updating in order to take advantage of new features and security/bug fixes?