To make this process simple without any hiccups the first thing to do is to go to the Android Play store or the Apple App Store and install the Microsoft authenticator app. This keeps your email and files safe and is the same kind of protection that you have on your bank accounts.
Links to both of them are below
It will look like this, as long as its installed you dont need to do anything more for the moment but please make sure that you allow all prompts when installing
Once you have this installed head over to www.office.com and sign in using your new email address and password that you have been given.
After clicking sign in you will be prompted to set up multifactor authentication.
To set this up follow the on screen prompts. You will be asked to scan the screen with your new Authenticator app on your phone and you can also have a choice to get a phone call from Microsoft where you will be asked to press and key from the key pad. If you opt to receive a text you will be sent a 6 digit code, enter the code into the designated box in the same way as you do when logging into your bank account and other systems.
After completing these steps you will be signed into your new Office 365 account
Now you are ready to go download and setup outlook on a mobile device.