When I publish the model-driven app, it leads to this page. I click to see my app, it doesn't work, but it returns to this page again. I don't know what the issue here. I watched some tutorials and see that left corner is "Dynamics 365" but mine is "PowerApps". I'm not sure this causes the issue?
Should be a temporary glitch. Navigate to https://<orgname>.crm.dynamics.com/apps url & click the app thumbnail again to see. Or refresh the browser, even https://home.dynamics.com should work like AnkUser said.
Regarding the left top branding logo, probably the new trial orgs getting the PowerApps logo rather than Dynamics 365. You can change it to your company logo under Settings - Customizations - Themes. That should not be a problem. You can click that PowerApps Logo to see the top Jewel menu reloads fully.
