oh, i was you meaning for this first beta, the answer is AUHD, for the second one i think you need to be on the first beta ZUID, maybe on AUHD, we will see
For the second one you also need to be on whatever version the user who captures the link is on before updating
For the second beta you need to fetch the URL from ZUID, otherwise the users need to downgrade to stable to install second beta package.
China's Samaung has started internal Android 12 OneUI 4 Beta internal testing.Is look like Beta is on the corner
http://fota-secure-dn.ospserver.net:80/firmware/DBT/SM-G991B/nspx/9a1e8afda5be4836b11e47220f1832f7.bin?px-time=61ab4c95&px-hash=c7157a18f8f114257c9aaaea6cc87f88&px-wid=0114966-WSA211005111010&px-wctime=2021-10-05%2011:10:10&px-unum=&px-nb=UGtezEZ854jbmFcvWGxLEA==Beta 2 released today, awaiting exynos version sharing link please.
Source => https://www.sammobile.com/news/new-galaxy-s21-one-ui-4-0-beta-update-is-here-download/
About that...I have a tutorial (taken from an old beta thread) to fetch beta links:
How to capture the update.zip file to share with other people: 1. Download HTTP canary app from playstore 2. Open HTTP Canary app 3. Start the update by pressing "download" and don't pause it 4. Go back to canary app and start it and it will grab the link for you