I was setting up a new site and installing all my plugins. When I tried to install GP Premium, I got an error message the the zip file was not a zip file. Other plugins could still be installed with no problems. I disabled all the active plugins and GP Premium installed just fine. Here is a list of the other plugins I had installed. One of them must be the conflict.
Elementor
Elementor-Pro
Code Snippets
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UpdraftPlus
WooCommerce
GeneratePress 2.2.2
GP Premium 1.7.8