This started out trying to install the Brave web browser (which has a shell script for installation) but ended up being an apt-get update issue.  When run it I get:

Ign:1 cdrom://[Devuan GNU/Linux 6.1.1 excalibur amd64 - desktop 20260425] excalibur InRelease
Err:2 cdrom://[Devuan GNU/Linux 6.1.1 excalibur amd64 - desktop 20260425] excalibur Release
  Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMsHit:3 https://brave-browser-apt-release.s3.brave.com stable InRelease
Get:4 https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease [29.1 kB]
Get:5 https://packagecloud.io/slacktechnologies/slack/debian jessie/main amd64 Packages [5,230 B]
Hit:6 http://deb.devuan.org/merged excalibur InRelease             
Get:7 http://deb.devuan.org/merged excalibur-security InRelease [37.9 kB]
Hit:8 http://deb.devuan.org/merged excalibur-updates InRelease
Reading package lists... DoneE: The repository 'cdrom://[Devuan GNU/Linux 6.1.1 excalibur amd64 - desktop 20260425] excalibur Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.


I have run:

apt-cdrom add

and

apt-cdrom -a -d /media/cdrom0 add    (the /etc/fstab entry for /media/cdrom0 is: /dev/sr0        /media/cdrom0   udf,iso9660 user,noauto     0       0)

as requested above and the "cdrom" was added to sources.list (shown below) but apt-get update still returns the same messages

deb cdrom:[Devuan GNU/Linux 6.1.1 excalibur amd64 - desktop 20260425]/ excalibur contrib main non-free non-free-firmware

deb http://deb.devuan.org/merged excalibur main contrib non-free non-free-firmware
deb-src http://deb.devuan.org/merged excalibur main contrib non-free non-free-firmware

deb http://deb.devuan.org/merged excalibur-security main contrib non-free non-free-firmware
deb-src http://deb.devuan.org/merged excalibur-security main contrib non-free non-free-firmware

# excalibur-updates, to get updates before a point release is made;
# see https://www.debian.org/doc/manuals/debian-reference/ch02.en.html#_updates_and_backports
deb http://deb.devuan.org/merged excalibur-updates main contrib non-free non-free-firmware
deb-src http://deb.devuan.org/merged excalibur-updates main contrib non-free non-free-firmware


Mounting and looking at the mounted DVD (/dev/sr0) and comparing it to a Debian 12 and Kali (which uses Debian) iso, all three have a Release file under /dists/<distribution name> so I don't know what is wrong.
The only unique thing about this install is that it is a VM under KVM.  I hope that's not the issue.
What do I do now?  I don't want to disable the check because I see that the ability to do so will be removed in the future.
Thanks for any and all help, I appreciate it.