Can you confirm that your nuget feed is available?
When trying to access this using the package manager console I am recieving the following error:
[Infragistics] The V2 feed at 'packages.infragistics.com/.../Search() returned an unexpected status code '503 Service Unavailable: Back-end server is at capacity'.
I have reproduced this issue, and I spoke to our engineering teams about it. They have looked into it and restarted the Infragistics licensed feed server, and everything appears to be working fine now.
Please try this again on your end and let me know if you are encountering any further issues.
Please let me know if you have any other questions or concerns on this matter.