Hello Avonshee and welcome on Gothicat World
A clan is for classify/ arrange your creatures, for examples you can sort by species (one clan for flamiris, one for lunaris etc.) or create a clan for your favorite creatures, but you can have no clan at all if you prefer
You can create a clan with
when you clik the button "My clans" in your creatures' page
And the send button is for the search for creatures
for example I select flamiris, position 4, I click send and this flamiris shows up
For your problem that you can't type into the box, it looks like a "bug", you can make a post on the technical problems section on the forum
Hope I've been clear enough
Have a good day; enjoy ^^