Typically, you can appoint any adult as your proxy unless your HOA bylaws stipulate additional restrictions. It’s a good idea to consult with your HOA to avoid losing your vote at the last minute.
Designating someone who lives under the same HOA is helpful, as they’ll better understand the community’s rules and how people living in the community feel about certain issues. However, no matter who you choose, make sure you can trust them to represent your wishes accurately during the HOA meeting.