After downloading, when clicked, it doesn’t start installation, rather it opens the ARK program (which is a file compression/decompression application).
Also tried with YAST, after import, it tells: “Error loading package list from /home/jamil/Downloads/musescore-2.1.0-1.1.x86_64.rpm”.
su -
zypper in http://download.opensuse.org/repositories/multimedia:/musescore2/openSUSE_Leap_42.1/x86_64/musescore-2.1.0-1.1.x86_64.rpm
or
zypper in /home/jamil/Downloads/musescore-2.1.0-1.1.x86_64.rpm
PS, openSUSE Leap 42.1 is out of maintenance (EOL) so you should look at upgrading your system.