Hi,
By results, do you mean the result content fields are blank? Are you using ACF to print the contents of posts or something similar? By default the plugin requests the post contents from wordpress, which ACF should integrate to. You can change those here: https://i.imgur.com/9Pmh8c8.png
If a custom field is defined for the content, you should be able to select that there as well.
If you are using multiple custom fields for the post contents, then using the advanced title and content fields feature might be better for your case – as there you can enter as many custom field names as you want.
The search results page cannot be controlled by the plugin (the layout), that has to be custom coded within the theme.
ACF is not separated from the regular custom fields, it integrates with them. You can choose the ACF custom fields for search on the General Options -> Sources panel, as well as use them as filters, or the upper mentioned advanced title/content fields.