There is a bit more to consider when preparing Rpi5 for Volumio OS. The whole guide you can find here (if you have not already):
There seems to be a variety of shipped Rpi5 with NVMe ready and without, hence:
When using raspi-config the PCIE_PROBE=1 will not be automatically set (unless latest version has the change).
If you can see “Install to Disk” when booting Volumio OS from Micro SD, you are good to go.