[R-SIG-Mac] Installing gfortran

[Göran Broström]

Trying gfortran-f51f1da0-darwin20.0-arm64.tar.gz from
https://mac.r-project.org/libs-arm64/ (following instructions), download 
and unpack,

but no sight of gfortran in /opt/R/arm64/bin

so the building of my package fails.

clang -arch arm64 -I"/Library/Frameworks/R.framework/Resources/include" 
-DNDEBUG   -I/opt/R/arm64/include   -fPIC  -falign-functions=64 -Wall -g 
-O2  -c c2f.c -o c2f.o
/opt/R/arm64/bin/gfortran -mtune=native -fno-optimize-sibling-calls 
-fPIC  -Wall -g -O2  -c chek.f -o chek.o
make: /opt/R/arm64/bin/gfortran: No such file or directory
make: *** [chek.o] Error 1


Of course, there is a warning on that web page (so why the link to it?) 
saying that

IMPORTANT: All binaries are moving to a unified repository under 
/bin/darwin<ver>/<arch> with manifest file to simplify automated 
installataion. Go to /bin/darwin20/arm64 for latest Big Sur arm64 
binaries. The following is only kept for legacy access.

but there I cannot identify (by name) any file that could contain a 
fortran compiler.

To summarize: I need help.

Thanks, Göran