nrf53 USB as mass storage with SDCARD enable ok but doesn't work


I am here, again! I am trying to use the USB of nfr5340dk or my custom board as mass storage with SDCard.

I am sure the SDCard works... in the same project I can read and write files without problems, but when I enable the usb, the USB_enable() function returns that there is not a problem, but from the PC I can't see the device, and no enumeration too.

The first question is: How does USB bind with SDCard? I saw that for internal flash, the overlay file contains these rows that I don't have:

/delete-node/ &storage_partition;

&mx25r64 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		storage_partition: partition@0 {
			label = "storage";
			reg = <0x00000000 0x00020000>;

/ {
	msc_disk0 {
		compatible = "zephyr,flash-disk";
		partition = <&storage_partition>;
		disk-name = "NAND";
		cache-size = <4096>;

second question: The application must exit from the main to works like in this other post?