Hello,
To my understanding in the current version of telemac, Dredgsim was replaced by "Nestor" so that's why it doesn't find any module called that way. Also there is a need to update some minor options in "cmd_xxx" instructions to get a successful compilation.
I haven't used windows version in a really long time so I manually updated the cfg file from v7p1 to get it done. If you want to try it just replace the file under the path below with the attached file. Make a backup first.
C:\opentelemac-mascaret\v7p3\configs
Then launch telemac's parallel cmd window using the shortcut created in the desktop and execute:
P.S: This should update the failed build of telemac and hopefully get you a working compilation, although without nestor or mascaret. I don't need those modules and also have an older and incompatible version of gfortran.
Hope it helps,
José Díaz.