Yes, the evaluation YumaPro SDK can be used by anyone for research or evaluation purposes.
Get free tools from the YumaWorks Developer Portal
Additionally, if you want to learn more about NETCONF & YANG you should look at the resources and information here: http://www.netconfcentral.org/
and Open Source NETCONF projects can be found here:
https://github.com/CESNET/libnetconf
https://github.com/CESNET/Netopeer
https://github.com/OpenClovis/OpenYuma