You have installed the .Net Framework 3.5 or .Net Framework 3.5 SP1 successfully and without error but Server Manager and IIS report that either 3.0 or 2.0 is installed.
Frameworks 3.0 and 3.5 still use the core 2.0 ASP.NET Framework and simply add additional features. So the highest version you will see in IIS for Application Pools or Applications will be 2.XXX or 3.0 depending on if 2 was installed before 3.0.
How to check the version installed:
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