ALPHA (fka Tech Alpha 2) Invite Emails

16 hours ago, airace said:

Regarding "I have to use my outlook account to unlock the PC?" - Yes.

A (local) Windows account is not related/associated to your Gamer account/password in xbox unless you used the same account to login to your desktop.

For those who login to PC using a local account you might run into this issue that I did which initially prevented me from getting to the Alpha download. This was because I have multiple outlook.com/hotmail.com/live.com email addresses and my local Windows account was not connected to anything xbox. So if you have two or more outlook/hotmail/live accounts and you received the Alpha invite on the 2nd email address, you will not see the Alpha download:

1. You login to Windows desktop (e.g. myAccount-ID01) you notice that the gamertag and account are not the same as the email address on which you received the Alpha invite.

2. You used [email protected] (or @hotmail.com or @live.com etc.) to receive the Alpha invite (and you use that ID for login to Outlook/XBox etc. via a browser).

In this scenario, you need to go into Windows settings - Accounts - Family and Other users - and click on your "[email protected]" and click Allow. (If "[email protected]" is not listed, you can add it using the + icon).

Next, right-click the Start button and Sign-out. Now sign back in using the "[email protected]" username and password - If this is the first time logging into this PC as that user, it will ask you to assign a PIN during this process.

Once you are logged in using "[email protected]" and password, open up the Alpha link from the email invite, and download the Insider Hub. Open the Xbox console on this PC and the Alpha download will be seen.

Hope this helps.

This might have been your experience but I can tell with certainty that you do not need to login to your Windows 10 computer using a Microsoft account. 
Using a local account for the PC and a Microsoft account for the xbox piece is all you need.