Use version v0.1.2-alpha and Linux as an example. Linux's users choose linux, and Mac's users choose darwin.
logs: the directory stores all logs.
logit.conf: the config file of logger. Check logit's documents to know more usages.
postar.ini: the main config file of postar. Check _examples/config to know more usages.
postar-xxx.exe: the executable binary file.
If you don't know how to set, get some helps from your smtp service.
Maybe the executable binary file doesn't have competence, so you can use chmod to have.