To integrate Arena in Vimeo OTT it is necessary to use Google tag manager.
You should create a new tag within the Google Tag Manager, choose the Custom HTML option in the tag configuration, and include the embed code of the format if the desired chat (in page, bottom, side, overlay, or iframe if it is better).
After creating the tag on google, a tag code will be generated, this code will be inserted into the Vimeo OTT in the Google Tag Manager Container ID field, Vimeo explains where to find this field here in this article: https://vimeoott.zendesk.com/hc/en-us/articles/360047081734-Add-Google-Tag-Manager-ID
After that the chat should appear on your Vimeo OTT screen.
For more information please contact our chat support within the dashboard.