Followed the instruction on playonlinux.com and got this from the update step.
apt-get update
Ign:1 http://deb.playonlinux.com etch InRelease
Ign:2 http://deb.playonlinux.com etch Release
Ign:3 http://deb.playonlinux.com etch/main amd64 Packages
Ign:4 http://deb.playonlinux.com etch/main all Packages
Ign:5 http://deb.playonlinux.com etch/main Translation-en_US
Ign:6 http://deb.playonlinux.com etch/main Translation-en
Ign:3 http://deb.playonlinux.com etch/main amd64 Packages
Ign:4 http://deb.playonlinux.com etch/main all Packages
Ign:5 http://deb.playonlinux.com etch/main Translation-en_US
Ign:6 http://deb.playonlinux.com etch/main Translation-en
Ign:3 http://deb.playonlinux.com etch/main amd64 Packages
Ign:4 http://deb.playonlinux.com etch/main all Packages
Ign:5 http://deb.playonlinux.com etch/main Translation-en_US
Ign:6 http://deb.playonlinux.com etch/main Translation-en
Ign:3 http://deb.playonlinux.com etch/main amd64 Packages
Ign:4 http://deb.playonlinux.com etch/main all Packages
Ign:5 http://deb.playonlinux.com etch/main Translation-en_US
Ign:6 http://deb.playonlinux.com etch/main Translation-en
Ign:3 http://deb.playonlinux.com etch/main amd64 Packages
Ign:4 http://deb.playonlinux.com etch/main all Packages
Ign:5 http://deb.playonlinux.com etch/main Translation-en_US
Ign:6 http://deb.playonlinux.com etch/main Translation-en
Err:3 http://deb.playonlinux.com etch/main amd64 Packages
404 Not Found [IP: 51.254.83.230 80]
Ign:4 http://deb.playonlinux.com etch/main all Packages
Ign:5 http://deb.playonlinux.com etch/main Translation-en_US
Ign:6 http://deb.playonlinux.com etch/main Translation-en
Reading package lists... Done
W: The repository 'http://deb.playonlinux.com etch Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://deb.playonlinux.com/dists/etc...amd64/Packages 404 Not Found [IP: 51.254.83.230 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.

Hi...

This appears to be the culprit. The server in this case is down or no longer in existence. I'm guessing the latter as Debian Etch is quite old and is no longer supported. If you take a look at the playonlinux distribution page here you'll notice that Etch is not even mentioned.

Are you still using Etch? If not, which distribution and version of Linux are you using? I was able find a copy of playonlinux for Jessie here. The other versions of Debian on the upper right corner of the page have copies as well.

Regards...