Hi,
I believe we’re already resolved this through the support system, but for everyone having the same question it is important to note that plugins and themes need to be installed through different management sections in the WordPress dashboard:
– themes are managed and installed under Appearance > Themes
– plugins are managed and installed under Plugins
Mixing the two will throw an error like the one you are seeing because you are trying to upload the wrong extension type to what WordPress is expecting in that uploader.