When installing EventSentry or launching the database wizard, I get an

This is caused by a missing Windows update. If Windows has not been recently updated, or if you've been installing nothing but Security-Only updates and Security-Only rollups, you might be missing a required dll file.

Either update your system so that you have at least one of the monthly update rollups which were released since January 2018, or manually install this specific update which fixes the affected dll files for your operating system:
https://www.catalog.update.microsoft.com/Search.aspx?q=kb3118401

After your system has been updated, you can successfully complete the EventSentry installer or the database wizard.

You may also encounter a crash of the EventSentry Network Servicse or EventSentry Collector, where the crash refers to the "api-ms-win-crt-stdio-l1-1-0.dll" file. This crash is also caused by the missing update and can be resolved using the steps from above.