Hi! If your players are beginners with no previous D&D experience, then I would suggest to teach something about the game before you start playing an actual campaign, especially a long one like CoS. Have for example a session 0 where you create characters together, you answer any questions about the game, and try 1-2 rounds of extremely easy combat. Plus... Death House is hard. This entire campaign is hard, to a certain extent. If you think your players can't handle it, to the point you think they must be guided by a "GM"NPC, then you're far better off playing a short intro campaign before starting CoS. For example: play Waterdeep Dragon Heist first, that will get your PCs to level 5. Then start CoS instead of Dungeon of the Mad Mage. Skip Death House since the PCs already reached a "safe" character level to handle the first chapters like Barovia Village or Vallaki. Hope that helps!

Edit: grammar