Why is there no place to report box 2 (net rental income) from schedule K-1

You didn't say what kind of Schedule K-1 you have. There are three different kinds, for an S corp (Form 1120-S), a partnership (Form 1065), or a trust or estate (Form 1041). I assume that your Schedule K-1 is for a partnership.

On the screen that asks what type of activity the partnership is involved in, you selected "Business - Box 1" (or you left Business selected by default and just clicked Continue). That's why TurboTax is asking for business income from Box 1. If you select "Rental real estate - Box 2" for the type of activity, then a couple of screens later it will ask you to enter the Box 2 amount. See the screen shot below.

If your Schedule K-1 has amounts in both boxes 1 and 2 you have to enter it as two separate K-1s, one for the business items and one for the rental real estate items. This is explained if you click Learn More on the screen that asks for the type of activity.