Unfortunately, Assetto Corsa EVO won't support CSP or Content Manager since it's an entirely new game and already includes features like rain out of the box. Its up to the mod creators to create something similar though, if modding will be supported at all - we are still in the dark about the extent of mod support, but what's promising is that it uses Kunos's engine, similar to the original Assetto Corsa. That's definitely a positive sign! However, don't expect mods from AC1 to work with EVO unless Kunos pulls off some serious magic, given it's running on a much newer engine. Fingers crossed for good mod support though!