In short, yes!
But for the longer version, you are allowed to upload the work of others that were made of your characters as long as you properly source them!
How do you give credit? You can tag them in your Unvale Profile if they have an account on this site or leave a link to where others can find them.
Without the proper credit you risk the work being archived which cannot be reversed. So remember to always give the credit where it's due!