The way that you'd utilize the site depends on how you answer the first two questions. Let the page translate and look under "borrow" for both.
If you just want a studio that is cheap and you don't expect much, if any, foot traffic, "Apartment" should be fine. I would just sort by price and then look for something that is within your range. However, if you want to do something commercially, "Store office" is what you would want to pick.
Either option you choose, you'll get a map of Okinawa to narrow down your search.
And then narrow down the area even more by expanding this box and selecting "Chatan".
If it's an apartment and you will be having foot traffic, be upfront and honest with the realtor and explain what you plan to do in the space. We held a very high-traffic business in our apartment and made the owner aware of our business. They ended up not having a problem with it, but did want to charge us an extra 7000 yen per month.
Some things that you won't find listed on that site are co-op spaces. This is a fairly new concept, at least that I've seen advertised openly. A co-op would give you a private area that you could at least paint in as well as shared spaces where you could set up times for viewings if the co-op scheduling permits. Though, the space is very limited with this and might make you feel like you're boxed in, whereas you can get an apartment that is four times the size for twice as much money.