Yes it's OK to put warm soup in the fridge.
There's no need to completely cool the soup down before refrigerating it.
The refrigerator will cool the soup down even when it's warm but it just takes the refrigerator a bit longer to cool the warm soup down when it's warm.
Although it's not advisable to put warm or hot food in the refrigerator there really is no harm in doing so.
The refrigerator will just run a bit longer to cool down the food you put into it and the food will not be harmed.
It would be better to put the hot or warm soup or other food into the refrigerator or freezer and get it cold faster than just leaving the food at room temperature.
However it's okay to leave soup out for 2 hours until you refrigerate, freeze it or eat it.