Calibre doesn’t natively support reading DRMed files, but there are anti-DRM plugins which are trivial to install. You need to provide a legitimate Kindle serial number for Amazon DRM, as it uses that to de-encrypt the files. When you add the file(s) to your library, the plugin automatically runs as a file conversion. It basically converts it from a DRM-locked .epub/.azw3 to a DRM-free .epub/.azw3 instead. Since Calibre already has file conversions built in, the plugin simply uses that existing system to spit out a DRM-free version of the same file, then it adds that to your library instead.
Calibre doesn’t natively support reading DRMed files, but there are anti-DRM plugins which are trivial to install. You need to provide a legitimate Kindle serial number for Amazon DRM, as it uses that to de-encrypt the files. When you add the file(s) to your library, the plugin automatically runs as a file conversion. It basically converts it from a DRM-locked .epub/.azw3 to a DRM-free .epub/.azw3 instead. Since Calibre already has file conversions built in, the plugin simply uses that existing system to spit out a DRM-free version of the same file, then it adds that to your library instead.