pin location ?
You can put the pins anywhere in the cell if the design is not harmed by this choice. But in case of not placing the ports at the cell border, you shall guarantee that the routing blockage layer has sufficient slots for routing , otherwise the router will not be able to route signal to a pin covered with blockage layer from all directions.
Also you may raise the ports up to a metal layer that is not used in your cell, in this case , you will not need to define routing blockage for this layer and the router will reach the pin freely.