Hi Marco!

We address Section 508 accessibility here in our policy documents: https://help.totaralearning.com/display/TPD/Totara+Learn+Accessibility You'll particularly want to have a look at the VPATs. Compliance is an ongoing process reviewing new features and functionality to make sure they meet the 508 standards, and if they fall short, the VPAT details the issues and what is being done to remedy the situation. 

The other thing to keep in mind is that even though the software meets Section 508 requirements, the content being added must also be done to address accessibility. Closed captioning and/or transcripts with videos, alt text on images, no text embedded in an image, etc are the responsibility of the content creators.

Thanks!