I think you're using the plugin on a version of Elgg which isn't supported by the plugin.

File tools isn't compatible with Elgg 3.x, because we haven't had a need for it to be updated.

If you wish for it to be updated contact us at info@coldtrick.com and we can discuss what would be involved to update the plugin (time / costs).

As I said, I am afraid to deactivate aalborg_theme since it gave me a fatal error that I did not know how to recover from and had to reinstall Elgg. This time I would lose some work I have done in it.

If you can wait, I can give it a quick look tomorrow under 2.3.16, which is the one I should be using.

Thanks a million!! That worked and I am in business with both Tutor LMS and Lessons. 

Just a question though. I notice that for a course or lesson you can add just one file. In the use case we have a lesson may have multiple documents - document, video, image, even sound file. In effect the ability to load a folder vs a file. The File Tools plugin provides some of that capability on the Files tab. However, it expects end users (teachers in my case) to zip the files up, something they are not tech savvy to do, and it does not support some formats, such as Google docs that teachers often use. Ideally, it would associate a folder structure for a lesson with other folders or files in it. 

I am asking for a lot :-(

I notice that for a course or lesson you can add just one file. In the use case we have a lesson may have multiple documents -

It should be easy to allow multiple uploads, it will require to change the upload button to "multiple" and loop through the files in the action.

Ideally, it would associate a folder structure for a lesson with other folders or files in it. 

Alternatively, instead of uploading the files via lessons' plugin, you could embed them with the files plugin. If you need folder structure, I strongly suggest you to try this plugin:

https://github.com/ColdTrick/file_tools