Thanks for inquiring Aspose.Slides.
I like to share that Aspose.Slides supports the versions in download section up to one year. As per Aspose policy, after one year they are removed from download section as Aspose.Slides does not provide support on the basis of old versions. The support is always provided on the basis of new version and I would like to suggest you to please try using Aspose.Slides for .NET 6.8.0 on your end that is much improved product version with SmartArt rendering support as well.
We are sorry f or your inconvenience,