A couple of possibilities. First, the RCexl ignition supplied with current EME engines is rated for 7.4V to 12V, so you will need the correct supply voltage for it to work correctly. Many people don't catch that change from previous ignitions. Second, have you had a twin before or at least one that has the carb on the bottom. Think about it for a minute, with the carb on the bottom, smaller twins can struggle to pull the fuel charge into the engine at cranking speeds.Sometimes when choked the fuel just sort of pools on the choke plate and never gets into the engine. Some twins start best with the throttle set just above idle for initial flips until it pops, some at full throttle (of course this is with the choke closed). Then retard the throttle to just a tiny bit above idle and flip until it starts. Some just won't start at full idle but will crank right up with the throttle advanced a tiny bit. You need to learn what your particular engine / carb likes best for a starting procedure. I flip at full throttle, choke on until it pops. Always flip the prop with authority to get a decent airflow into the engine.

There is nothing particularly different about your EME than any other modern, decent quality RC gas engine. They all start pretty much the same and I doubt your EME will be any different once you find the right starting combination.