As part of the deployment process for the SharePoint Online microservice, an app service needs to be created to host the microservice.
Create the app service
Log in to your Azure portal as a user with the necessary permissions to create an App Service.
In Azure, navigate to All Services > App Services and create a new App service.
Under Project Details, select a Subscription and then create a Resource Group for the App Service.
Under Instance Details, enter the following information:
Name — Enter a name for the app service
Publish — Select Code
Runtime Stack — Select .NET Core 3.1 (LTS)
Operating System — Select Linux
Region — Select the appropriate region
Click Review + Create.
Click Create.
After the deployment of the App Service completes, click Go to resource.
On the Overview page, copy and save the URL for the app service. You will need this when you create the service principal application for the app service in Azure AD.