On the web browser:
https://outlook.office.com/mail/
You can also find Outlook on the Microsoft portal:
https://www.microsoft365.com/?auth=2
Windows computer:
How do i install Outlook Client on my Windows computer?
Mac computer:
How do i install Outlook Client on my Mac?
Linux computer:
You cannot get an Outlook application for Linux computers. On Linux computers, you can use Outlook as a browser, or you can download another email application that will work on your computer. Here's how to get Exhange email into the Thunderbird email client:
How to use Exchange email with Mozilla Thunderbird
Note! The instructions are made for mobile phones, but will work as well on tablets thanks to the same operating system. Also the operating systems of Apple's iOS phones and iPadOS tablets are very similar so you can use this guide to install Outlook on your Apple tablet as well.
Android phones/tablets:
How do i enable email on my personal Android phone?
iOS phones and iPadOS tablets: (iPhone, Apple)
How do i activate email on my personal iOS phone?
Email can also be used with other applications, but Digital Services do not provide support or guidance on how to use them.
More instructions can be found on Microsoft's own website: https://support.microsoft.com/en-US/outlook