Complex sentence: Under the Convention, copyrights for creative works are automatically in force at creation, without being asserted or declared: an author need not "register" or "apply for" a copyright in countries adhering to the Convention.
Split into simpler sentences: Under the Convention, copyrights for creative works are automatically in force uopn their creation without being asserted or declared. An author need not "register" or "apply for" a copyright in countries adhering to the Convention.