How do I allow the site to open without turning off the VPN
Many web sites do not allow access from known VPN IP addresses. They do this for copyright, legal, security, and political reasons. There is nothing a VPN provider can or should do to circumvent these legal protections. See this How to Geeks article. https://www.howtogeek.com/403771/why-do-some-websites-block-vpns/
If this is happening for your charge card web site, there is nothing you can do. Try contacting the web site support to see if they have any suggestions.