How do I add haste as a default for survival players?

putting SURVIVAL here doesn't work: alwaysHaste: "CREATIVE",

If you have Mod Menu installed, you'll have a much easier time adjusting the settings by using the in-game menu. Just navigate to "Mods" from the main menu, search for Custom Portals, and click the config icon near the top right of the screen. I wouldn't recommend editing the json config file directly as it's not intuitive, but if you must do that, you'll need to put "YES" in the alwaysHaste field.