Hi Rick,
You can sign in to the Azure portal using the owner/admin Entra ID account for your Office 365. Next, scroll down and click on Subscriptions, then click Add button.
Below screenshot shows Azure portal Home page when the current default tenant doesn't have an associated Azure subscription. If you don't see Subscriptions under Azure services scroll down and there will be Subscriptions icon under Navigate:
After clicking on Subscriptions on the portal Home screen, it takes you to below, where you click Add:
On the Create a subscription screen, the Plan box will likely be empty, so click on Add a different type of subscription, select Free Trial or Pay-As-You-Go and follow the prompts, entering information as requested. In screenshot below, I blanked out Billing account/profile/section for privacy reasons:
Depending on your specific situation you may want to choose one of the offers under "All other offers", but for company that wants to use Azure for production and doesn't have Enterprise/Customer agreement Pay-As-You-Go is most common.
Once you get your Azure subscription set up it will use same Entra ID tenant as your Office 365, so if you want to grant certain users access to Azure you can.
Please click Accept Answer and upvote if the above was helpful. If something is unclear please add a comment.
Thanks.
-TP