For Example: (from 3rd link you provided):
https://github.com/podonoghue/usbdm-firmware
The above is a GIT repository containing source for the flash routines used on the target processors.
https://github.com/podonoghue/usbdm-eclipse-makefiles-build
The above is a GIT repository containing source for application programs.
What does "I cannot open it" mean?
Are you having trouble with them being GIT repositories?
You can download a ZIP from code button:
