I'm working today, so will be hard for me to help you from my phone. Are you using @RBoy software?
I use the software from here:
I use the 4th DTH, universal z wave lock
And the 1st smart app, lock multi user management.
You'll have to pay for access and use of his software, also you'll have to clear the lock codes in the lock to allow the software to set new ones.
He has guides for installation and setup and is very helpful if you get stuck.
I think the step you describe is telling you to select the custom DTH from the device setup. It will default to a stock handler but you'll have to log into your IDE edit the device and where it says what handler it's using, select that list. Then scroll to the bottom of the list. If you got your custom Device handler installed correctly it will be listed on the bottom after all the stock handlers. Select it to be able to use the options it provides.
There's is better instructions on the forum, and or WIKI. If @RBoy doesn't jump in with better directions or links to them. I'll try to do it late tonight after work.