As a prerequisite, Python must be installed, see Python on Windows.
Install BornAgain from PyPI:
$ python -m pip install bornagain
Frequent problems include the following:
Having more than one Python interpreter installed on the system may cause subtle errors. Managing their co-existence is possible, but may require special skills. It may be preferable to uninstall all Python versions but one.
BornAgain is a 64-bit application and requires a 64-bit Python3 installed on the system.
The Python version number (major.minor) must be supported by the BornAgain
wheel. When installing from PyPI, pip selects a compatible wheel
automatically or reports that no matching distribution is available.