Impossble de retouver Insider Alpha

You must be invited to become an Alpha Insider or Alpha Skip Ahead Insider, to do so You must Very active in Xbox, doing missions and report the bugs You see in the system, as much as You do this, so You Will be Very close to become an Alpha Insider. You
must be at least in Delta preview to become an Alpha Insider, but You Just need to be an Insider to be invited to become an Alpha Skip Ahead, but this one is very rare to be invited and there is a certain number of people to be invited, no more than that,
If You were not invited to be Alpha Skip Ahead certain time, so You must wait a Second chance when they Will invite New members.

Hi there.

I'm assuming that you are referring to the Alpha Insider update. If so, report the bug via. the insider hub.

Notes on the update: Xbox insider release notes alpha 2010-200901-0000.

Go to Reddit Xbox insiders for more information.

You need to either be in the uk or us and be an xbox insider on ring beta, alpha or alpha skip ahead.

The current Xbox Insider Alpha release build is RS_XBOX_RELEASE_2007\19041.3432.200623-0000 (2007.200623-0000)

Source:
https://news.xbox.com/en-us/2020/06/24/xbox-insider-release-notes-alpha-2007-200623-0000/

You don't unless you join the insiders program which is on alpha skip and alpha only

Which both are invite only