With online crypto gambling, you'll be funding your online casino account with cryptocurrency instead of regular fiat currency, such as USD. You'll be able to fund your account by sending crypto directly from your coin wallet to your personalized casino coin wallet address. This process should be pretty instant.
In general, using a VPN for sports betting and gambling is legal if such an activity is allowed in your country or state. At the same time, the legality of online casinos and lotteries varies, as every country has its own laws and regulations in this regard.