I just purchased KeyViz Pro via lemonsqueezy and PayPal.
On my order summary, the Download button for the msi installer:
...leads to an unstyled 'Access Denied' XML message.
You really should publish a support email address prominently on your website so that paying supporters can access help, rather than having to raise GitHub issues for things like this.
Please can you provide me with the msi installer for the Pro version that I have purchased.