Purchase EA Azure subscription + M365 subscription

Hello,
Our customer has O365 subscription in place and mailboxes are migrated to o365 platform.
As part of next set of migration, they would like to purchase a new EA azure subscription.

I was going through , https://docs.microsoft.com/en-us/azure/cost-management-billing/manage/microsoft-365-account-for-azure-subscription#get-an-azure-subscription-using-your-microsoft-365-account , which talks about purchasing Azure subscription with existing 0365 subscription admin so as to use same AAD .
However I would like to understand , is this can be EA subscription or PAYG subscription?
How to purchase EA subscription linked with existing O365/M365 subscription?