The Garden with the entering portal. From the Garden where you'll find the portal there is a greeter. He's your slave like servants in your POH. But you need to OSRS gold purchase one from Ardougne too. Even in case you've got a servant on your POH. In the guild you can not utilize the servants for your POH. You can just buy special guild servants.
The same as POH servants, POG servants may request you wages after an amount of time so if you paid 5,000gp for him then you'll have to pay the same quantity of money after some time. That means that you won't only pay their price for a single time. More expensive servant takes will invest additional time without asking for the wages.
Your clan members can donate in these chests. The best part is that you can use them to your guilds needs. As an instance, you have to buy RuneScape Mobile gold pay your servant his wages, but don't have enough money. You check the donation chest and when there is enough money you pay the servant.