Please download 3D Slicer exclusively from the official website or from the past downloads section and proceed to install it on your PC. 

It is important to note that the available plugin is tailored for version 4.10.2 only. 

After launching 3D Slicer, go to the top menu and select Edit->Application Setting to open the Settings window. 

From the list on the left, choose Modules, and then drag and drop the downloaded Seg Muscle folder into the Additional module paths box on the right. 

Alternatively, you can click the '>>' button next to the box and select the path directly using the Add button.