Here it is May of 2020 and I am having exactly the same problem in Windows 10.
In the SoundTap trial period, I was able to record a stream, start a new record of a new stream and finally exit SoundTap.
Unfortunately, after my recent purchase, I can only record one stream. When I try to start the recording process for the another stream, I get the "Directory Permission" message. I also cannot exit SoundTap even by using Windows 10 Task Manager.
The only way to exit the program is to "crash exit" windows and reboot.
I am going to try the suggested reload of the program to