How to install PCL for 16.04, PPA not working

I tried to follow the PPA for the prebuilt binary:

sudo add-apt-repository ppa:v-launchpad-jochen-sprickerhof-de/pcl
sudo apt-get update
sudo apt-get install libpcl-all

but I get a failure message like:

W: The repository
'http://ppa.launchpad.net/v-launchpad-jochen-sprickerhof-de/pcl/ubuntu
xenial 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://ppa.launchpad.net/v-launchpad-jochen-sprickerhof-de/pcl/ubuntu/dists/xenial/main/binary-amd64/Packages
404 Not Found E: Some index files failed to download. They have been
ignored, or old ones used instead.

Any idea what is wrong?

After looking at the first link in your error message, getting into the dists directory, it seems that this PPA does not support Xenial, as there is indeed no such directory.

This link however, provides a link to a pre-built DEB file you can download and install using dpkg (not recommended as it is just a Dropbox link and the file could contain malicious code) and also explains how to build it from source (recommended as it only installs trusted packages and downloads the code from the official GitHub repository, which can be considered a trusted source).

I have not tested it but as it looks like a standard compile procedure and as mentioned above, downloads the source code from an offical repository, you should be fine following the steps there, given you do not want to install the DEB file which would be perfectly fine, as I would not want to do it, too.