The current vote percentages at your site, Harris/Trump/Stein 63/18/18, suggests that your sample so far is quite unrepresentative. Is there a reason to expect that to change?
As far as this poll goes, it's a self-selected sample, which has its own problems.
Not just 20somethings. I'm in my 50s and lots of people in my general age group also refuse to answer the phone when an unknown caller calls.
Even fewer will consent to taking part in a poll even when they do answer the call, in large part because so many of those calls are push polls and other political marketing rather than real polls. That means they're no different than other scam spam calls.