You cannot play in Minecraft Pre-releases or Minecraft releases-canditade.

My cousin can't access Minecraft from the pre-release versions, up to the current version 1.17 release canditate, he's not an original account user unfortunately he's not able to buy one. If it's any help he uses Minecraft Tlaucher. I submitted this same report on the Tlauncher website, and am waiting for their response. If you can fix it. Thanks