SUMMARY


STEPS TO REPRODUCE
1. ~$ sudo add-apt-repository ppa:vikoadi/ppa
   ...
   Err:6 http://ppa.launchpad.net/vikoadi/ppa/ubuntu bionic Release
     404  Not Found [IP: 91.189.95.83 80]
   Reading package lists... Done
   E: The repository 'http://ppa.launchpad.net/vikoadi/ppa/ubuntu bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
   ...
2. ~$ sudo apt-get update
   <... same errors as above ...>
3. ~ sudo apt-get install indicator-kdeconnect
   ...
   E: Unable to locate package indicator-kdeconnect

OBSERVED RESULT
errors mentioned above - cannot find a Release file.

EXPECTED RESULT
Should work.

SOFTWARE/OS VERSIONS
Windows: 
MacOS: 
Linux/KDE Plasma: Ubuntu 18.04 LTS
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
I used to use Zorin OS that was a variation of Ubuntu 16.04 LTS and it installed just fine there with the same CLI instructions.