There could be a few reasons why guests can't access teams in Teams Manager:
Guest access might be disabled for the specific team. Team managers can control this setting during team creation or in the team's settings.
There might be a policy in place that forces guest access to be disabled. This can be set in the 'Policies' section of Teams Manager settings.
The overall guest access feature might not be enabled in Teams Manager. This setting can be found in the 'Setup' section of Teams Manager settings.
To resolve this, you can check these settings and adjust them as needed. If you're still having trouble, it's best to reach out to your organization's Teams Manager administrator for help.