Only members physicalDevice, device, instance are required. However, you should inform the library which Vulkan version do you use by setting VmaAllocatorCreateInfo::vulkanApiVersion and which extensions did you enable by setting VmaAllocatorCreateInfo::flags (like VMA_ALLOCATOR_CREATE_BUFFER_DEVICE_ADDRESS_BIT for VK_KHR_buffer_device_address). Otherwise, VMA would use only features of Vulkan 1.0 core with no extensions.
VMA supports Vulkan version down to 1.0, for backward compatibility. If you want to use higher version, you need to inform the library about it. This is a two-step process.
+VMA supports Vulkan version down to 1.0, for backward compatibility. If you want to use higher version, you need to inform the library about it. This is a two-step proces.
Step 1: Compile time. By default, VMA compiles with code supporting the highest Vulkan version found in the included <vulkan/vulkan.h> that is also supported by the library. If this is OK, you don't need to do anything. However, if you want to compile VMA as if only some lower Vulkan version was available, define macro VMA_VULKAN_VERSION before every #include "vk_mem_alloc.h". It should have decimal numeric value in form of ABBBCCC, where A = major, BBB = minor, CCC = patch Vulkan version. For example, to compile against Vulkan 1.2: