On Ubuntu 16.04:
Download the Linux .zip file from our downloads page: https://me-download.wickr.com/#/version/me
Decompress (extract) the .zip file to your local machine.
You may already have a program installed that will install .deb files, but if not, please install Gdebi from the software center or run the following command in terminal:
sudo apt-get install gdebi
Once you have Gdebi installed, run the following commands changing the version numbers to match the files you currently have in a terminal:
sudo gdebi wickr-qt_5.9.4_amd64.deb
sudo gdebi WickrMe_4.53.07-01_amd64.deb
Run the WickrMe.desktop file.
On Other Linux Distributions:
First, you will need to install snapd. Snapd is pre-installed on many Ubuntu distributions, but if yours is not one of them or you have a different flavor, the instructions for installation can be found at https://docs.snapcraft.io/installing-snapd/6735
Then, search in the snap store for Wickr and choose Wickr Pro and/or Wickr Me (they both work simultaneously on one device) and use the appropriate instructions to install: