Linux Wallet install fail - Unknown FIle Type??

[ObiSandwich]

Linux LMDE 4
FILE: blocknet-4.3.3-x86_64-linux-gnu.tar.gz

Followed the wallet installation advice here: https://docs.blocknet.co/wallet/installation/

Double-click the blocknet-qt file to begin the installation process. (If it fails to open on double-click, you may need to give executable permission to the file: Either sudo chmod +x blocknet-qt in Debian terminal, or Right-click property, give executable permission.)

Updated file permissions like this...

But could not get it to open or install, instead got this error...

When installation requests a file to be "double-clicked", I thought that meant the file needs to be either an .appimage (eg. BlockDX software) or a .deb file - are the installation instructions above for Ubuntu only?

Has any body successfully installed this wallet on LMDE, Mint or Debian OS?