Collapse-o-matic will not expand

Hi. I am new to all of this stuff but I have been able to set up a simple wp site and actually do some html edits when needed.
Plugins are great and this one looks great too but I can’t make it work.
I do the needed edits to the title and text but the latter will not collapse.
The site page where this can be found is http://www.apel.org.ar/?page_id=9

Thanks in advance for any help.

Gerardo

https://wordpress.org/plugins/jquery-collapse-o-matic/