Discord JS: Extracting data from a collection

I have a command where I want to write the id from a user in a Voice Channel into an array. So far I managed to write the whole collection of the user with joinedTimestamp etc. Now I want to extract the ID from the user from the collection. My command looks like this:

client.on('messageCreate', (message) => {
    let waitingroom = message.guild.channels.cache.get("952324088762867722")
    let player = [];
    let isadmin = message.member.roles.cache.has(adminRole);

    if (message.content.toLowerCase() === prefix + 'startgame' && isadmin) {
        player.push(waitingroom.members);
        console.log(player);
    }    
});

And this is what I get from the array when 2 users are in the waitingroom:

[
  Collection(2) [Map] {
    '392776445375545355' => GuildMember {
      guild: [Guild],
      joinedTimestamp: 1646940658665,
      premiumSinceTimestamp: null,
      nickname: null,
      pending: false,
      communicationDisabledUntilTimestamp: null,
      _roles: [Array],
      user: [User],
      avatar: null
    },
    '849388169614196737' => GuildMember {
      guild: [Guild],
      joinedTimestamp: 1647168003344,
      premiumSinceTimestamp: null,
      nickname: 'Test-Account [Nils]',
      pending: false,
      communicationDisabledUntilTimestamp: null,
      _roles: [],
      user: [User],
      avatar: null
    }
  }
]

But I only want the ID’s from the users from the collection. I appreciate any help.