Download the last stable version here:
Open downloaded file and double click on TunnelBlick icon
Confirm the next dialog
Enter your SYSTEM (MacOS) password
Click the button "I have configuration files"
Download all profiles from this page:
The icon of the installed application should be appeared in the upper system menu. Click it and "VPN Details" after
Drag one by one (to the left part) of the required configuration preloaded files in step 7
Choose All Users or Only Me as you wish
Confirm this action with your system (macOS) password
Now you should have such window. Click on "Connect"
Enter your VPN99 login and password. Click on "Save in Keychain" to save your account.