autosave custom fields

Hello!
I'm using Metabox builder, created a custom field textarea with id "csspagina".
When i preview the page the custom field is not previewed to frontend.
I tried to add in custom settings: autosave-true

Followed docs: https://docs.metabox.io/creating-meta-boxes/#field-group-settings
Same problem as: https://support.metabox.io/topic/previewing-metaboxes/

Could you help me?

Thanks