I don’t know whether the VC++ redist for VS 2017 runtime is downward compatble with VC++ redist for VS 2015. I guess probably not if the history of VS2013, VS 2012, VS 2010 and so on were to be examples.
Since current version of Xojo requires the VC++ redist for VS 2015, it means that current Xojo is written with VS 2015 therefore all apps built will require VC++ redist for 2015. This is safer and guarantee no problem. When Xojo begin to be written with VS 2017, then at that time, VC++ redist for 2017 become a compulsory dependency, no longer 2015, but only for “that new” version.
Visual C++ Redistributable Packages install runtime components of Visual C++ Libraries on a computer that does not have Visual C++ installed. The libraries are required to run applications that are developed by using the corresponding version of Visual C++.[/quote]
Use the 2015 ones we give you in the Extras dir next to your install of Xojo
Extras > Windows Runtime contains both the individual files or the installer