Yes the pin and the sight must be removed, it's not hard to do but be careful not to cause damage with an incorrect punch.
The next step is to remove the spring that was under the sight. There is a groove under where the spring was that a part with a threaded sleeve fits into.
Then a screw goes through the rail/base that screws into that threaded sleeve and 2 screws one on either side screw in where the pin went through.
Solid as a rock. It really is in my opinion the absolutely strongest scout mount for a Mauser on the market. - Bill