Students cannot access audio recordings

Hi All,
I am wondering if anyone can help.
I recently signed up to Kami as a educator and took advantage of there free trail for schools during COVID-19.
I have sent out an assignment with instructions and discussion points recorded as voice comments on the document for the students to listen to whole they complete the work. I have since tested this with a child and apparently they are not able to see any.

They are instead prompted with - ‘in order to hear these audio comments please ask your teacher to upgrade’.

However when I go into Kami subscription options it doesn’t allow me to upgrade as the trail has already ben selected. According to this trial I should have access to ALL the features and so should the students.

Hopefully someone can help with this.