Once you install OS 10.3.2 or 10.3.3, you cannot downgrade to earlier versions due to anti-theft protection.
Ensure you have the STL100-2 model. You can check this under Settings > About > General . Blackberry Z10 Stl100-2 Autoloader 10.3.3 Download
Official link download autoloader 10.3.3. - CrackBerry Forums Once you install OS 10