For people who might read this thread later looking for a solution, I received a response from PdaNet+ support yesterday that solved my problem:

Do you happen to have Zone Alarm or AVG installed...

PdaNet uninstalls when the network driver doesn't install so it is not in programs to give the ability to install Legacy USB driver. I have gone through the helps on PdaNet+ and have not found a...

I am attempting to install PdaNetA5214 on my HP 64-bit laptop with no success. I have the app installed on my Galaxy s4 from Straight Talk (SM-S975L) which is Android 4.3 and cannot be upgraded. The...