Is it allowed to use VPN?
I don't see any reason to use VPN here. If you can use it without VPN, then why is there a need to use VPN?
Even if you use VPN, you might face restrictions. You can use it as is and see if you can use it smoothly without VPN.
Some gamblers use VPN by default when browsing the web. There’s nothing wrong to use VPN if your purpose is not to bypass country restrictions of the casino.
On this case, Gamba clearly mentioned that they are against the use of VPN which means user shouldn’t use it but on some casino it’s valid to use VPN for privacy purposes.
Also VPN let you play some games that is not accessible using default IP. This is not against the casino ToS since it’s just the default restriction of the provider.