Update: After a System Restore (which I had planned to do anyway after intalling Yosemite), I redownloaded Capture Polar and reinstalled it. This time I was properly prompted enter my password to make changes, and the license file installed successfully; however, when I tried to unlock it over the internet, I instantly got an error message that said:
"Unlocking was refused due to too many recent unlock attempts."
That's a little odd, seeing as how this is the first time I've tried to unlock a license since the one time I installed Capture Polar on my older computer eight months ago....
I look forward to someone presenting a solution to this issue, as I'm quite eager to use Capture Polar on my MacBook.