Hello,
I don't know if you are still facing the problem, but after two days of trying different things finally I managed to successfully install it.
This is what worked for me:
1. Open NI Package Manager
2. Open the settings panel by clicking the icon in the upper right corner
3. Remove the check mark from "Automatically download and install missing dependencies from ni.com"
4. After that, search for the "Database connectivity toolkit" and install the desired version.
The installations finished without any problems.
I hope this is going to help somebody.
Regards
