I suppose the REIT for some reason believes their properties appreciate at a rate of 4%, giving 8% + 4% = 12% projected yield per annum.
However, actually properties do depreciate and not appreciate. A reasonable depreciation rate for properties is -2%. To maintain the real value of your investment, the REIT needs to invest into repairs at about 2% per year rate.
So, I would project you to have 8% cash yield (if we can believe that, because it sounds too high), 2% inflation and -2% depreciation, giving a total yield of 8%.
However, I don't really believe the 8% cash yield is reasonable. Where I live, properties yield more like 4-5%. That would give 4-5% total yield.
TL;DR: there are better investment opportunities than this. If you nevertheless invest into this, keep in mind that a single investment should be at most few percent of your portfolio.