The access to the Guild Vault can be granted to certain roles in the guild, limiting deposit as well as withdrawal rights for both smaller Guild Stash or larger Guild Treasure Trove individually. Access to the Deep Cave is tied with the same deposit and withdrawal rights as the Treasure Trove even if not explicitly stated in the rank permissions. The entire vault is accessible by guild members with proper permissions by contacting a Guild Banker in any of the major cities or by researching and activating the Vault Transport upgrade.
Guild Vault can be upgraded to hold up to 250 inventory slots, 50 slots in Guild Stash and 100 slots in Guild Trove, and the Deep Cave upgrade granting additional 100 for the Guild Trove.
It will cost the guild 52,500 influence to gain access to fully upgraded guild vault and may take up to one month in time to research.