I bought Bamboo (Server) 10 jobs, 0 Remote Agents. I downloaded the zip file option atlassian-bamboo-7.2.1-source.zip. Extracted it and then followed the instruction and couldn't find start-bamboo.bat in bin folder which to start bamboo.
welcome to Atlassian Community!
I have just downloaded
and can confirm the file is in "bin" directory.
All I can imagine is that you did not download atlassian-bamboo-7.2.1.zip (as you wrote "source") or a local virus scanner eliminated the bat-file for whatever reasons.