Not entirely sure based on the information alone, but typically a complete failure to launch the game is the result of incorrect installation or using incompatible versions of the game and mod pack. Have you checked those things yet?
If by the newest you mean the version available to the public and not the one available for Patreon subscribers, then yes. If you are a Patreon subscriber and have that version, you need to go on the Discord and download the modpack there for that version of the game.
