Indonesian passport holder, can I apply for transit visa after I land in Guangzhou Baiyun airport?

Nini, you do not need any kind of visa because your layover in Guangzhou will be covered by 24 hour visa free transit scheme. When you land in Guangzhou, you will approach a transit counter where you will apply for a temporary entry permit by presenting your flight tickets. This is free of any charge. After a short check you will be allowed to exit the airport.

Just proceed with your travel plans because there is nothing to worry about.