Thanks for your patence in advance ;-)
Newby installing and learning but fell at the firt jump.
Debain 10 on a VPS.
I'm SSH into it and I'm getting so far then seeing...
--2020-03-28 15:08:16-- http://dvswitch.org/install-dvswitch-repo
Resolving dvswitch.org (dvswitch.org)... 220.127.116.11
Connecting to dvswitch.org (dvswitch.org)|18.104.22.168|:80... connected.
HTTP request sent, awaiting response... 200 OK
Saving to: ‘install-dvswitch-repo.2’
install-dvswitch-repo.2 100%[====================================================>] 782 --.-KB/s in 0s
2020-03-28 15:08:16 (61.1 MB/s) - ‘install-dvswitch-repo.2’ saved [782/782]
The Repository file already exists, exiting
Hit:1 http://security.debian.org/debian-security buster/updates InRelease
Hit:2 http://deb.debian.org/debian buster InRelease
Hit:3 http://deb.debian.org/debian buster-updates InRelease
Get:4 http://dvswitch.org/ASL_Repository stretch InRelease [4,806 B]
Hit:5 https://packages.sury.org/php buster InRelease
Err:4 http://dvswitch.org/ASL_Repository stretch InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 72147EC1E788D4C3
Reading package lists... Done
W: GPG error: http://dvswitch.org/ASL_Repository stretch InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 72147EC1E788D4C3
E: The repository 'http://dvswitch.org/ASL_Repository stretch InRelease' is not signed.
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.