How to tell if your Michigan medical marijuana clinic is legit?

hello i've been dealing with migraines since 2004 i've tried numerous medications and all have found to be ineffective so i found myself searching for a Michigan medical marijuana clinic i've found a place while searching on craigslist called Southlake Medical Group, PLLC they have 100.00 dollar certification they are having a event at a hotel with doctors but im curious if they're legit here is the website http://www.southlakemedicalgroup.com/Home.php how can i be sure they are legit im not looking to waste my money or get in any kind of problem with the government or something