See solution below.
Explanation:
Step 1: To create a general-purpose v2 storage account in the Azure portal, follow these steps:
* On the Azure portal menu, select All services. In the list of resources, type Storage Accounts. As you begin typing, the list filters based on your input. Select Storage Accounts.
* On the Storage Accounts window that appears, choose Add.
* Select the subscription in which to create the storage account.
* Under the Resource group field, select RG1lod11566895
* Next, enter a name for your storage account named: az400lod11566895stor
* Select Create.
Step 2: Enable boot diagnostics on existing virtual machine
To enable Boot diagnostics on an existing virtual machine, follow these steps:
1. Sign in to the Azure portal, and then select the virtual machine VM1.
2. In the Support + troubleshooting section, select Boot diagnostics, then select the Settings tab.
3. In Boot diagnostics settings, change the status to On, and from the Storage account drop-down list, select the storage account az400lod11566895stor.
4. Save the change.

You must restart the virtual machine for the change to take effect.
Reference:
https://docs.microsoft.com/en-us/azure/storage/common/storage-account-create
https://docs.microsoft.com/en-us/azure/virtual-machines/troubleshooting/boot-diagnostics