In Biden's closing remarks he told people to go to "joe30330"
Someone immediately registered the domain and redirected it to their page:
http://joe30330.com
https://joshforamerica.com
Under Donate, it says:
"We're flattered about your interest in donating to our campaign! Unfortunately we're still having trouble resolving a process issue where ActBlue thinks our campaign is "not legitimate." We're sure this issue will be resolved quickly, but in the meantime, please feel free to donate to our good friend Pete Buttigieg's campaign."