If something's satisfactory it's okay — acceptable, but maybe not great. When you take a course pass/fail, your grade will be satisfactory if you meet all the requirements and do a reasonable job, or unsatisfactory if you don't.
Try not to confuse satisfactory and satisfying. If you've cooked a satisfactory turkey for Thanksgiving, your guests aren't getting sick or making excuses to leave the table, but they're probably not asking for seconds either. But if your turkey is satisfying, everybody is complimenting you on your culinary skills and probably sitting back in their chairs with contented smiles on their faces.