Hello, I created an admin claim, but I didn’t find how I can add other players to the server claims?

I want a certain group of players from different parties to build at spawn

If you're using a permission mod, there's a permission node which is "xaero.pac_server_claims" by default that lets a player claim/unclaim as the server and access server claims in server claim mode:
/openpac-claims server-claim-mode