The library does not compile

No, the problem is not solved.
Windows
nightly and stable build of mingw64(c:\msys64)
of_v0.12.0

MINGW64 /c/of_v0.12.0/libs/openFrameworksCompiled/project

make

Package glm was not found in the pkg-config search path.
Perhaps you should add the directory containing glm.pc' to the PKG_CONFIG_PATH environment variable Package 'glm' not found /bin/sh: line 1: return: can only return' from a function or sourced script
Package glm was not found in the pkg-config search path.
Perhaps you should add the directory containing glm.pc' to the PKG_CONFIG_PATH environment variable Package 'glm' not found /bin/sh: line 1: return: can only return' from a function or sourced script
makefileCommon/config.shared. mk:311: *** couldn't find glm pkg-config package or it's dependencies, did you run the latest install_dependencies.sh?. Stop.

Please explain what kind of tambourine I need to dance with, what rituals to perform, just to start using OF?

Start in libs/openFrameworksCompiled/project by reproducing the reported make command on the stated MINGW64 setup. Read makefileCommon/config.shared.mk around line 311 and inspect install_dependencies.sh, then determine what a successful build requires for the missing glm pkg-config package. Done means the project compiles without the reported dependency and shell errors.