We experienced the same issue as Sarah. Unfortunately, we did not find a solution here.
Here is how we could achieve a successful installation, maybe it can be helpful for colleagues who will also face this error in future.
First, temporarily turn off your anti-virus software including your software firewall.
Then, install the DI API separately: Uncheck "SAP Business One Client" and check "DI API".
If the DI API installation has been successful, install the client.