Verify that the Blacksands User Certificate and full Certificate chain are installed in your local environment.
There are three Blacksands certificates in the chain: Blacksands Inc CA Root, Blacksands Inc CA, Blacksands CA L3. There will also be User certificate that will include the first letter of your first name, last name, and a numeric identifier 'jdoe-1234'
These certificates must be 'Trusted'
If the Certificates are not there - make a request of your local Administrator and they can create the account and certificates.
If the Certificates are there but not trusted - trust the Blacksands Inc CA Root. This will provide trust through the entire chain. How do I trust the Blacksands' Certificates WindowsOSX?
If the Certificates are there and trusted - check your network security, items like WAF (Web Access Firewalls) may be blocking access to the site.