It's likely NOT ok!
The site you are using provides sports betting statistics. They provide data to partners who sign an agreement with them. They are unlikely to give the data away to anybody who wants without paying or at least signing an agreement.
To do Ajax with that site:
1. Make sure your usage is in accordance with their Terms and Conditions
2. they will either have to whitelist your server's IP address, or else whitelist ALL IP addresses. See above for why I think it's unlikely they would whitelist all IP addresses!
3. Make sure you match http/https. That is, you cannot mix and match http/s between your own site and theirs. They both have to be the same.
4. You may have to use a real server for your site. (Not just loading from local files on your PC.) Depends on browser. Some browsers (Chrome, for example) will not to Ajax if the page was served from a local filesystem.