If you have an active subscription, you can sometimes find older versions (typically only back to 2022 or 2023) by clicking the three dots next to Photoshop in the Creative Cloud Desktop app and selecting "Other versions" .
If you are looking for this specific version due to its low system requirements or unique features, it included: Why can't I download an older versions of some programs Adobe Photoshop CC 2015 Download Free Trial Version
While a direct "CC 2015" trial is unavailable, here is how you can legally access Photoshop today: If you have an active subscription, you can