Microalbuminuria is a marker of early kidney disease in Diabetes and other diseases, and is also present in persons who have high blood pressure where the presence of microalbuminuria may be a marker of early kidney disease, but more importantly a marker of higher cardio-vascular risk.
Concerning your test result, we cannot make any conclusions if you have this condition or not, because as you notice microalbuminuria is expressed as mg/g of creatinine, so in the urine sample you give the laboratory has to measure both albumin and creatinine and calculate a ratio expressed in mg/g, this will correlate more with the 24 hour excretion of albumin by your kidneys.
So the first thing you should do is repeat the urine test, morning samples give the best results. If the test result you do confirms the presence of microalbuminuria, the cause of this should be investigated and appropriate treatment depending on the cause will be given.
The most frequent causes are Diabetes and High blood pressure, and other diseases affecting the kidneys.