The page compares five years of rent with the principal and interest on a purchase, plus a sale cost you can read on the form. Rent can grow at the rate you enter. The buy side uses the home price, down payment, and mortgage rate on the form. Any investment return you enter is applied only to the case the form labels.
If rent is $2,200 a month and does not change, five years of rent is $132,000 before moving costs. The buy side depends on the price, the down payment, and the rate you type. The verdict is the difference between those two paths over the years on the form, not a lifetime forecast.
Repairs, property tax, insurance, and homeowners association fees are left out unless a field on the form asks for them. It is not a full cost of owning, and it is not tax advice on the mortgage-interest deduction.