Plugin not displayed on Plugins Section
When downloading from the Github releases tab be sure that you are downloading the latest plugin release for the version of Craft you are using.

In the case of Sprout Reports:


v0.x releases are for Craft 2
v1.x releases are for Craft 3


When in doubt you can look at the files within the plugin folder and try to determine which version of Craft the plugin is for. Most Craft 3 plugins will have a composer.json file and src/ folder.