The refered tutorial. The commands used in order:
1)wget https://desktop-download.mendeley.com/download/apt/pool/main/m/mendeleydesktop/mendeleydesktop_1.19.4-stable_amd64.deb
2)sudo dpkg -i /mendeleydesktop_1.19.4-stable_amd64.deb
3sudo apt -f install
It fails as soon as I input my password as required in the second step. This is what the terminal shows me:
dpkg: error: cannot access archive '/mendeleydesktop_1.19.4-stable_amd64.deb': No such file or directory
Also, in the Mendeley website the current versions of the software seem to be incompatible with 20.4.