This is an easy one to fix. Just navigate to the Manage Domains section of the control panel and look for the sub-domain you have created to host the Advanced Poll.
At the far right side of the screen (under the "Web Hosting" column -just to the left of the "X") you will see a link titled "edit".
Click this link and you will be presented with a form detailing how the domain/sub-domain is to be configured, including radio buttons for which version of PHP to use. Just "select" the PHP 4.42 button, and "save" the new configuration by clicking the "Change fully hosted settings now" submit button at the bottom of the form.
Wait until the change has taken place (while the change is pending, a small "clock" icon will appear next to the sub-domain in the Manage Domain screen). When that icon goes away, the change should be complete (note: to check the icon status, use the link to Manage Domains - do not "reload" the "edit" page/repost the data - or you will submit the change again, and have to wait again, etc).
When the change has taken place, return to the Goodies->One-Click Installs screen and install your Advanced Poll. Follow the directions in the confirming email, and you should be good to go (just be sure and be patient, as the installer is sometimes overly optimistic on how quickly it will be ready to go ) Good Luck!