Social preview
The preview title, description, and image are what Reddit (and Discord, Telegram, and similar) show when your link is posted. Without them, previews fall back to plain MyRedLink branding. Set them per link under Advanced settings.
Tracking
Google Analytics ID (G-XXXXXXX): fires a page view in your GA property when the link is opened.
Meta Pixel ID: fires your pixel on the redirect page.
Both are optional and per link. MyRedLink's own click counting works regardless.