正解：

See the Explanation below for complete solution.
Explanation:
Before you start
Log in to SAP BTP Cockpit.
Open the correct Global Account.
Go to Directories.
Open Human Resources.
Open the EU HCM Dev subaccount.
This matters because the task must be completed in EU HCM Dev, and the service instance must be created in the specific Cloud Foundry space activity-recording. SAP Help also confirms that the HTML5 Application Repository is used in the Cloud Foundry environment and that the app-host plan is the host service used to store HTML5 application content.
Step 1 - Open the Cloud Foundry space
In EU HCM Dev, go to:
Cloud Foundry
Spaces
Select the space:
activity-recording
SAP Help describes creating Cloud Foundry service instances by first navigating to the subaccount, opening Cloud Foundry Spaces, selecting the target space, and then using that space's Services > Service Instances are a.
Step 2 - Open Service Instances in the space
Inside the activity-recording space, go to:
Services
Service Instances
This is the Cloud Foundry-space-level location used for creating service instances in that space.
Step 3 - Start creating the new instance
Click Create.

A wizard opens for the new service instance. SAP Help describes this as the standard cockpit flow for creating service instances in Cloud Foundry spaces.
Step 4 - Choose the required service
In the service selection, choose:
HTML5 Application Repository Service
SAP Help documents the HTML5 Application Repository as the service used for centrally storing HTML5 applications' static content on SAP BTP in the Cloud Foundry environment.

Step 5 - Choose the required service plan
Select the service plan:
app-host
SAP Help states that the app-host service plan is used to deploy applications to the HTML5 Application Repository.
Step 6 - Enter the instance name
Set the service instance name to:
html5-eu-hcm-dev
Then continue and confirm creation.
SAP Help recommends using a CLI-friendly name for service instances, and the task gives the exact required name.

Step 7 - Verify the space is correct
Before final confirmation, verify the target Cloud Foundry space is:
activity-recording
This is important because Cloud Foundry service instances are created within a specific space, not only at the subaccount level.
Step 8 - Create and confirm
Click Create or Finish.
Wait for the status to change from in-progress to created.
SAP Help notes that after creation, the instance appears in the service instances table and its status can be checked there.
Final expected result
Inside EU HCM Dev, in Cloud Foundry space activity-recording, you should have a service instance with:
Service: HTML5 Application Repository Service
Plan: app-host
Instance Name: html5-eu-hcm-dev
Common mistakes to avoid
Creating the instance in the wrong subaccount; it must be EU HCM Dev.
Creating it in the wrong Cloud Foundry space; it must be activity-recording.
Choosing the wrong service; use HTML5 Application Repository Service.
Choosing the wrong plan; use app-host. SAP Help specifically links app-host with hosting deployed HTML5 app content.
Typing the wrong instance name; use exactly html5-eu-hcm-dev.