is it possible to reach the macau airport by evening (1500hrs) if i'm staying around yuexiu park in Guangzhou?

It is possible, but the time is tight.
From Yuexiu Park Station, you can take the local subway line 2 to reach local South Railway Station. At this train station, you can take the intercity train to reach Zhuhai Train Station. Zhuhai Train Station is just near the Gongbei Port. Pass the port, you will reach Macau. There you can find Macua bus AP1 to take you to reach the airport directly.