Having same issue while trying to start “Learn Bash by Building a Boilerplate” on macOS Monterey v12.4, both with Mozilla & Safari. Cookies are enabled and no browser extensions.
Hello, i wanted to share that i had faced the same issue. Closing the browser, turning off wifi and then back on seemed to fix the issue for me. Maybe give that a shot!
For Firefox, Settings > Privacy and Security > Enhanced Tracking Protection > deselect anything that might block cookies or ease them down to not include third party cookies. Choose which trackers and scripts to block.