It is not a requirement that you in advance advertise on BostadsPortal to create a rental contract.
You can freely administer contracts and inspection reports on BostadsPortal without using the other functions. You are of course more than welcome to advertise your rentable. All of our tools are available for free.
When you want to create a contract, and do not in advance have an advertised rentable, then you only need to start by typing in the address for the rentable and you're good to start writing your contract.