Buying RE to rent is more like purchasing a business than investing by clicking a button. So the question is kind of like "where does buying a franchise fit into the investment order recommendation?" It's apples to oranges.
Some folks go all-in on RE, and that is probably the quickest way to exit one's 9-5 job forever. But they are trading the 9-5 for the irregular obligations of running a small business, even if they hire a PM. Someone who FIREs on investments alone, OTOH, is truly passive and free of work obligations. Between these extremes are folks like yourself, who take a hybrid approach mixing active and passive investments.
Because physical RE can only be purchased in big chunks, hybrid investors will need to sell some of their passive investments during some periods of time so that they can make a large down payment (usually 25% of the value), plus closing costs, plus setting aside a repair budget and working capital. Then, presumably, when they have enough RE, they return to their regularly scheduled investment order. To illustrate, suppose an investor saves up $100k in their taxable + Roth accounts using the standard investment order. Then they stop investing per the standard investment order, and in fact sell assets to make a $125k down payment plus costs to set up a small RE business. With that done, they return to the standard investment order the following year. They may choose to repeat the process to grow the RE portfolio in the future. At some point, most landlords get tired of the part-time job and liquidate their RE to buy passive investments again.