Hi Kirsty,
Thanks for sharing the screenshot. The error message "Access denied for the resource" usually means your account doesn’t have permission to access the Teams content you're trying to open.
Here are a few things to check:
Make sure you're signed in with the correct Microsoft 365 account.
If you're trying to access a specific team, channel, or file, confirm with your admin that you’ve been granted access.
If your organization uses conditional access policies, those might be blocking you.
Your IT admin can use the Correlation ID and Timestamp from the error to trace the issue in the logs.
Is your teams managed by a company/organization?
Or is it your personal one?