What OS X version do you have? Is the install button you're referring to on the download page, or on the installer itself after you have downloaded the installer? Please post screenshots (The specified item was not found.) of the behaviour your observing, it'll help to troubleshoot the issue.
Hi Maria. Thanks for reaching out. I'm running 10.8.5. It's from the Adobe page that there is no "INSTALL NOW" option.
Also I tried uploading the screenshot but it wouldn't take… hmmm. It's a 104kb file that was in a PNG format but I exported it as a JPEG just in case but neither will upload to show you
Sometimes privacy or anti-tracking add-ons like Ghostery or Privacy Badger will cause the behavior you're describing. You should disable them (or allow everything on the page) during the installation process.
A flaky network connection can also cause this behavior. Typically refreshing the page or coming back in a few minutes will resolve things if it's really just a transitory network problem.
As a short term workaround, you could download Google Chrome, which includes a built-in version of Flash Player.