The idea behind this Fortunes of Ravenloft scene is that it makes different Curse of Strahd campaigns actually different to some extent, in case a player is playing the same adventure again (why would he?) or has gotten information from somebody who already played it. In general I do like a certain degree of randomness, e.g. dice rolls, to be able to affect the outcome of an adventure, in order to make it more interesting not only for the players, but also for the DM.

However, for the Fortunes of Ravenloft I would strongly advise to not do the random determination of those 5 story elements in front of the players. First of all, it is a good idea to already determine the locations before the players arrive at this event, because some locations or allies might be in the village of Barovia, which is before the group reaches the fortune teller. And second, not all locations and allies are equally suited for the campaign. For example the random ally could turn out to be no one, a dead guy that would need to be raised to be able to help, a mad girl who thinks she is a cat and would need to be cured before she can help, a simpleton, a child, or the archmage Mordenkainen. Depending on your style and your group, you might really not want to use some of these options. Likewise the locations, if randomly determined, could vary from finding the powerful artifacts very early in the game, to them all being somewhere in Castle Ravenloft, thus making exploration of the lands of Barovia less useful.

My recommendation would be to do a Fortunes of Ravenloft card reading in advance for yourself, and then considering the consequences of the random results you got. If there is anything in there that you as the DM dislike and find not suitable for the campaign you want to play, draw another card, until you get a result you like. In Roll20 I have already done this, and distributed the cards I drew on the Tarokka Reading Board page included in the adventure, face down. For the card reading I can just flip the cards and it still looks like a real fortune telling. If you play Curse of Strahd at a real table, you can use some trickery: Put the 5 chosen cards in the right order aside behind your DM screen, let your players shuffle the rest of the Tarokka deck, take the deck back behind the screen and secretly add the 5 cards on top, then proceed openly with the fortune telling. If you absolutely prefer to never "cheat" as DM, you can do that too, but you'll have to live with results that might not be all that interesting or counter to your plans for the campaign.