Dear Juan,
I usually get this error when the user does not have the required access rights, e.g. to change an attribute, or to create/delete an object. Make sure to set the appropriate access rules in the Entity settings.
Alternatively, if you don't want to have a user be given direct access, place the change/create/update/delete in a Microflow, and trigger that microflow from your workflow. Make sure that in that Microflow “Apply entity access” is set to "No”
Hope this helps; if it did, please mark as correct.
Best regards,
Wouter