impossible to verify macOS during install on external drive

Hi,

I'm trying to install Catalina on an external drive attached to my MacBook Pro 16 i7 16Gb Ram 1Tb ssd.

I have downloaded the Catalina installer from the App Store (2 times) and the external drive is brand new.

I have correctly partitioned the external drive (multiple times)

Every time that I launch the installer after a few minutes I get the message "impossible to verify macOS Catalina" like some files is damaged and don't pass some checksum control.

I've also tried to change the usb c port, but the error is always coming out

Unfortunately I don't have other external drives drives to test, could be defective the drive?

Or I'm missing some step in the installation process?

I've googled but I haven't found any hint.