Extension not installing

I wrote an extension that has been approved for a while. I got an email from someone who bought the extension and couldn't install it on a Win computer with PS 2017. I have an extra computer and tried to install it also, as I just had the test files that were written with Brackets. I used the addons site to remove the extension, then tried to install it again. I said installing for a couple seconds, then the button on the website reverted back to "Install". This was a self-signed extension, and it looks like other people have purchased it, and have been able to install it. I've checked all the trouble shooting: CC app manager installed, file syncing on, allow internet access on, etc. Anyone have any ideas what is going wrong?