Wont really be that much of a problem in using free VPN's though specially on using Opera Browser which you could just easily switch up in between countries and without having any ads or something like others been
Using free VPN can be a problem when it comes to a site where multi accounts is strictly prohibited. Free VPN may gives you the same IP as other people who use the same free VPN. Once it is happened, the casino may detect the accounts as multi accounting because the accounts come from the same IP. It is better to use paid VPN while it does not cost too much money.