Losing my email 16th september

Hi all,

I’ve just received an email that I don’t understand that says this~

The safety and security of your information is top priority for Microsoft. To help keep your account secure, Microsoft will no longer support the use of third-party email and calendar apps which ask you to sign in with only your Microsoft Account username and password. To keep you safe you will need to use a mail or calendar app which supports Microsoft’s modern authentication methods. If you do not act, your third-party email apps will no longer be able to access your Outlook.com, Hotmail or Live.com email address on September 16th.

I have a Hotmail account that I have had for years. I have downloaded the Microsoft authentication app that asks for permission to sign in but other than that I have no idea!

I have a brain tumour so I struggle can some explain what I need to do in an idiot proof form please!