Read the faq pdf in the tools folder.
Follow those instructions first. Use expert mode so it doesn't force you to update modules.
You have to click k+dcan in the ista loader to start the way istap can work with usb dcan.

If after that you have problems connecting with ista/p like I did, you may need to do this:
Go to control panel, network connections, adapter settings. Find the one that was added by the installer, for usb or called virtual adapter. Inside the settings for that adapter, choose tcp/ip v4, change the address from auto to 169.254.0.8, subnetmask 255.255.0.0 (or whatever ista/p says the address when you pick the device in istap).
Restart computer and try ista/p expert mode again.

If you have issues, just ask here and include which operating system you are using.