Welcome to the forum! I've seen that using VPN is not allowed may I know the countries that is prohibited and also do you have a feature on where you will block immediately the IP from that restricted country so they would not be able to register or enter your website. I think that's useful.
You can get see the list of Restricted Countries in the section of conditions
https://www.slotman.com/terms-and-conditionsparagraph 3.6
Also, the Casino does not recommend using VPN, as this is prohibited by game providers.
If the registration takes place from the IP-address of a prohibited country, the platform will not give an opportunity to complete the registration.