I’m running Brave Version 1.0.0 Chromium: 78.0.3904.97 (Official Build) (64-bit) on macOS Catalina 10.15.1 and have successfully created a Brave Rewards Wallet with Uphold.
Welcome to community, and thanks for writing in. We are currently experiencing a server outage, and I believe this is the cause of your issue. I apologize for any inconvenience. You can track updates here - https://status.brave.com/.