...
Before you begin, see Determine if Centralized Deployment of add-ins works for your Microsoft 365 organization.
Download the manifest file here.
Sign in to Microsoft 365 for business with your work account.
Select the app launcher icon in the upper-left, and choose “Admin”.
TIP: “Admin” appears only to Microsoft 365 admins.In the navigation menu, choose Settings > Integrated apps.
Scroll down in the “Integrated apps” window. There will be some add-in management options. Click in “Upload custom apps” (see About the Microsoft 365 admin center).
Choose “App type” according to the add-in you want to install (either for Microsoft 365 apps or Microsoft Teams).
Then, you are able to select the manifest file (.xml) of the app you want to upload to Teams on your device: For this option, select “Browse” to locate the manifest file (.xml) that you want to use.
...
Download the manifest file here.
After uploading the .xml file, you will be able to select which Users in your organization should be able to use the add-in. The option are “Just you”, “Entire organization” and “Specific users/groups”.
Now, in the “Deployment” phase, you just have to check and accept the permissions for the app to function correctly and it will be successfully deployed.
...