Adobe has retired the activation servers for CS5. You may need to contact Adobe support or follow their official legacy documentation to receive a version that does not require online activation. Why Choose Photoshop CS5 Extended?
Note: Ensure you are using a key specifically for the "Extended" version to unlock 3D features. Step 5: Sign In (Optional/Legacy) adobe photoshop cs5 extended full version install
The "Extended" edition includes all the features of the standard version plus advanced tools for 3D and technical workflows. Adobe has retired the activation servers for CS5