Nextcloud Theming w/Docker Windows

I have started following the instruction on the client/building.rst page on github but havent made it very far. I am now stuck at step 7 getting this error:

CMake Error at cmake/modules/QtVersionAbstraction.cmake:8 (find_package):
By not providing “FindQt5Core.cmake” in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by “Qt5Core”, but
CMake did not find one.

Could not find a package configuration file provided by “Qt5Core” with any
of the following names:

Qt5CoreConfig.cmake
qt5core-config.cmake

Add the installation prefix of “Qt5Core” to CMAKE_PREFIX_PATH or set
"Qt5Core_DIR" to a directory containing one of the above files. If
"Qt5Core" provides a separate development package or SDK, be sure it has
been installed.
Call Stack (most recent call first):
src/CMakeLists.txt:7 (include)

hi, You managed to compile