Cant install magisk on my sm-n960f


hello ,I have followed your video about rooting my galaxy 8 it went all right few times.
I followed youre sm-n960f/ds video I did exactly everything you have shown with no problems
but there is no magisk ,when I try to install the magisk n9 s9 frome usb drve not working
when I try to download the apk from site …can not download ?
can you help ?