Don't know anything about psychotherapy, but know a little about computer security, if "HIPAA compliant" is keyword for "secure" an application for notetaking with encryption is bluenote https://bluenote.io/
Reason I mention bluenote over other methods - encrypted HD, etc - is its usablity features and very clear what is / isn't encrypted etc.
Back up regularly, because if you forget the master password, being encryption it's as good as gone (in fact to "securely delete" a hard drive, a good way is to encrypt it & forget the password).
This app is good for the sort of scenario where your computer is powered off & gets copied by border police, or where in the case forensic investigators subpoena you, you will have to be physically present - although they could still get a warrant for a keylogger to remotely exploit, I guess.