I can't get linux to make the repository!

Every time I use sudo apt-add repository… It won’t make it!
I always get this:
GDevelop is an open source game creation software, allowing to make games for the web (HTML5) or for Windows and Linux. No programming or coding skill is required! It is easy to use and powerful enough for advanced users.

Check out GDevelop website on compilgames
Sources are hosted on GitHub: http://github.com/4ian/GD
Help and support on the forums: http://forum.compilgames.net/
Press [ENTER] to continue or ctrl-c to cancel adding it

gpg: keybox ‘/tmp/tmpof5m4tc0/pubring.gpg’ created
gpg: /tmp/tmpof5m4tc0/trustdb.gpg: trustdb created
gpg: key 546CB231D3359AD7: public key “Launchpad PPA for Florian Rival” imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: no valid OpenPGP data found.

plz help me figure this out! btw i had to remove some of the links

There is no apt repository for GDevelop. Download the app image from the official website.