Explanation:
Graphical user interface, text, application Description automatically generated

Box 1: Change settings in app to preload app
You can optionally preload your app within Teams to increase performance.
Box 2: Change the permission for the custom app in Teams
As an admin, you can use app permission policies to control what apps are available to Microsoft Teams users in your organization. You can allow or block all apps or specific apps published by Microsoft, third-parties, and your organization. When you block an app, users who have the policy are unable to install it from the Teams app store.
You manage app permission policies in the Microsoft Teams admin center. You can use the global (Org-wide default) policy or create and assign custom policies. Users in your organization will automatically get the global policy unless you create and assign a custom policy. After you edit or assign a policy, it can take a few hours for changes to take effect.
Graphical user interface, text, application Description automatically generated

Reference:
https://docs.microsoft.com/en-us/powerapps/teams/embed-teams-app
https://docs.microsoft.com/en-us/microsoftteams/teams-app-permission-policies