I'm not positive about the exam, but most standardized tests given in the US have an option to make provisions for folks with learning disabilities. I don't see why this one would be different.
However, from what I have read about this particular condition, there are other aspects of the massage business that I would be concerned about. First of all, scheduling and keeping up with time. Massages last for a prescribed amount of time, usually covering full body, which means you have to be constantly aware of how much time has gone by and how much is left in regards to how much of the body is left to attend to. Also keeping track of scheduled appointments, and being on time for them, is very important in the professional world.
Also, not being able to mentally picture things that are not visible - and losing direction and orientation - would be a major handicap in massage therapy. You might only be touching skin, but you are actually working on the tissue below the skin - the muscles, the fascia, the circulatory system, etc. There are also organs, nerves, and other sites that are considered "endangerment" areas that you must be able to locate and avoid in order to massage safely. Beyond the basic safety measures, knowing where a specific muscle is located, how it's shaped, how it moves, which direction its fibers run, etc., is a major part of massage. People complain of specific pains all the time, and if they can indicate a general area, chances are pretty good you can find the cause of the problem very quickly if you palpate the rest of that muscle. If this is something you are unable to do in the abstract, massage is probably not going to be a good career for you.
You probably should discuss this with someone who specializes in learning disabilities and career placement, and see if they think this would be a reasonable career choice for you to pursue, and if not, what else might be a better fit.