One-on-one study is inherently resource-intensive, and I'm not surprised that sites that offer this service restrict it to Jews. If they offered their services to everybody then they'd have to pay attention to avoid matching non-Jews up with each other (at which point you're more likely to get Christian misinterpretations than torah study). And some of the people they're matching want to be matched with Jews for the (mutual) merit of torah study, which is an obligation for Jews but not for gentiles.
You are more likely to be successful if you look for classes or study groups. My synagogue has three different weekly text-study groups (two torah, one Tanakh) that people can drop into at any time; this isn't unusual. Nobody checks backgrounds; if people want to show up and learn, they show up and learn. I know we've had non-Jews show up at times. In cities with decent-sized Jewish communities, and/or Chabad, there are public classes of various sorts. Look for opportunities like these, instead of for one-on-one study.
One caveat: a baseline assumption of Jewish study is Judaism. There are other interpretations of our texts out there in the world, ranging from mistaken to fraudulent, and we've collectively been evangelized and attacked by some of these groups rather a lot. You didn't do that, of course; I'm just explaining background to say this: it's ok to ask questions (we love questions!), but try to ask them with some humility and from within the frame of Judaism as best you understand it, and if the leader seems to be trying to move on, let it go. As you attend more you'll get a sense of the group and this will be easier; initially, it's probably better to focus on listening and learning.