Just trying to help. I spent several hours tracking down why hostapd wouldn't recognise the standard nl80211 driver that covers something like 90% of chipsets in modern linux kernels. In this case it was an atheros based Alfa Network long range model.
In general, the most recent upstream version of hostapd should be used by default - both for security and functionality reasons. If and only if it doesn't work for a particular vendor chipset, then go ahead and install a vendor specific one. In that case, I don not recommend putting the executables in /usr/local/bin -- put them in the same directories that the APT package will deploy them in so that they can be overwritten by the package, or else register an alternative with the Debian alternatives system.
p.s. I know the security concern part might seem ridiculous to worry about on something like this, but hear me out. A quick search reveals that the known vulnerabilities on various versions of hostapd could allow a curious bystander to accidentally crash the hostapd software and possibly the UAV just by trying to connect to the wifiap and giving it bad information. Even the latest versions can have issues, but they generally tend to be in better shape than older versions. Vendor customized versions of software like this are the worst - 0.8 doesn't even show up on the list of versions which makes me think it isn't even a standard version number.
In any case, remember that on a UAV, a flight controller crash or network stack crash could lead to a UAV crash or loss of control that could be expensive and dangerous.
hostapd known vulnerability list:
Per my comment on instructions are everywhere: I was just trying to avoid duplication of instructions - there are instructions for setting up a raspberry pi as an access point in many different places. I don't want to be responsible for a specific configuration - just pointing everyone around the one speedbump I ran into.
Glad to be of service, and with this out of the way, my friend should be able to get his lightweight drone UAV in the sky soon. It should be lots of fun.