It simply won’t let me start Carl’s quest! Keep clicking start quest and it refreshes the page and still says 0/10 click to start :/

it's not Carl-specific, and the quest has indeed started, only the servers are not talking to each other. If you go back now, you will find you have a quest already going. Depending on how many times you pressed the start quest button, it may do this to you multibple times.

Never mind, it’s working now haha

yeah I just realised! Thanks!