Complime instructions Qt5 dlls missing

Hello,

I try to build musescore with these instructions https://musescore.org/de/handbook/compile-instructions-windows-mingw-git. But when I try to launch the .exe file in the end these errors appear:

Qt5Core.dll
Qt5Help.dll
Qt5Network.dll
Qt5Gui.dll
is missing from your computer.

What did I wrong?
I am sorry my english is bad and I am not an programmer.