Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
I am an Office365 subscriber and it doesn't eliminate the ads from Outlook.com, but a simple ad blocker such as AdBlock Plus will hide the ads for you. The only downside is that you will lose about 2" of horizontal screen width due to the blocked ads.
As for signing up- Microsoft doesn't even allow it. They advertise it, but it is impossible to sign up. I have tried contacting customer service about this and they don't have a clue and their responses are as useless as the ones you see from them above. I wouldn't doubt if their "customer service" is some algorithm that just replies based on what keywords appear in your question.
Anyways, just use an ad-blocker. Outlook.com is a great service, but Microsoft is effectively disconnected from their customer service. The lights are on but not one is home.