According to the documentation: https://docs.adobe.com/content/help/en/experience-manager-core-components/using/components/accordion...
Accordion properties should have "ID" field, in order to create deep linking.
But I don't see the "ID" field on my AEM 6.5?
Id option is introduce in core components from v2.10.0
Which version of WCM core components are you using? have you tried the latest version?
Accordion component introduced in core components version 2.5.0. Download it from here.
The link you are referring is using core component release 2.5.0 as a reference. Could you please verify if it is the same version in your instance as well?