Replace the sample link with your own working link (it must start with https://)
A website button still points at a sample link. Avox library templates come with example.com links as placeholders, and Meta reviews every link in a template, so a template can't be submitted until each button links to your own website. Links to localhost, and links that don't start with https://, are refused too.
Replace its Website URL with a working https:// link on your own website.
For a dynamic link, also replace the Example URL with a real finished link, then submit again.
Still stuck? Send AVX-3430 to hello@theavoxai.com along with what you were doing when it happened.