Installing nvidia-tlt, get SSL:CERTIFICATE_VERIFY_FAILED error

• Hardware Ubuntu16.04
• when running ‘pip3 install nvidia-tlt’, get
ERROR: Could not find a version that satisfies the requirement nvidia-tlt
ERROR: No matching distribution found for nvidia-tlt
Could not fetch URL https://pypi.ngc.nvidia.com/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=‘developer.download.nvidia.com’, port=443): Max retries exceeded with url: /compute/redist/pip/ (Caused by SSLError(SSLError(1, ‘[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:852)’),)) - skipping

Please share full command and full log. All the steps are appreciated as well.

ERROR: Could not find a version that satisfies the requirement nvidia-tlt
ERROR: No matching distribution found for nvidia-tlt
Could not fetch URL https://pypi.ngc.nvidia.com/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=‘developer.download.nvidia.com’, port=443): Max retries exceeded with url: /compute/redist/pip/ (Caused by SSLError(SSLError(1, ‘[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:852)’),)) - skipping

Please check TLT Quick Start Guide — Transfer Learning Toolkit 3.0 documentation
If possible, please try a machine with has ubuntu 18.04