I have solved the problem: the zip download has the files encrypted. I’m using a Vista 64 bit machine and all the file names were displaying green type (which I thought was unusual
). I now know that this means the files are encrypted - which was the reason for the "Failed include" message.
The solution is easy: right click on the parent folder (/assets/plugins/managermanager) and choose Properties. Click the Advanced button and uncheck
Encrypt contents to secure data.
(Not sure why the data needs encrypting on a free download
)