I'm in xbox insiders delta, sooooooo...

Delta is the lowest of all the rings

As mentioned you need to be beta and higher

That feature is only available to Alpha,Alpha skip aheads & Beta Insiders at the moment.

As you are in the Delta ring you will still need gold to play any games online.

Have you asked in the Insider Program forums over on reddit?

I am currently trying Delta ring. I will report here if it helps with crashing in late game.

UPDATE:

I was able to finish the game that was constantly crashing after updating to Delta ring release Xbox Insider Release Notes - Delta (2208.220715-2200) - Xbox Wire

If Omega ring has same fixes, then hopefully everyone will get this fix soon.

I will continue testing with Delta ring with all addons enabled (currently have extra civs disabled) with new game on huge map.

Seems you have to be invited to join the Alpha ring

https://support.xbox.com/en-US/xbox-one/console/xbox-insider-program

The current Xbox One Update Preview rings are:

• Alpha – Open on an “invite only” basis and receives updates at the earliest point in the preview window.
• Beta – Open to Xbox Insiders with a Program tenure of 3 or more months and an Xbox Insider XP Level of 5 or higher. This ring receives updates shortly after Alpha.
• Delta – Open to any Xbox Insider with a tenure of 1 or more months that has reached Xbox Insider Level 2 or higher. Depending on certain edge cases where further attention is required from Alpha or Beta rings, Delta Insiders may receive
  system updates before Beta, though this is not a common scenario. Additionally, while early system updates are not guaranteed across the Delta ring, all Delta Insiders will receive the update prior to GA.
• Omega – Open to anyone and receives system updates shortly before the GA (General Availability) release.