Okay, I'm thoroughly baffled.
I deduced that you want to "access my phone storage through wifi/bluetooth using my computer." Correct? Using your COMPUTER to access the phone, right?
But then you say:
So which is it?
When i said "I am trying to do the opposite i meant from what you did. You downloaded from phone to PC. My main concern is PC->Phone
Did you happen to read the 'help' for Airdroid? Just wondering. I never had! However, when I attempted to UPLOAD a directory using my default browser, SeaMonkey, I could SEE the 'select folder' option (along with 'select file'), but it wasn't selectable.
So I scratched my head wondering WTF?! Downloading worked, so it wasn't a file system issue Airdroid was having with my Linux hard drive...so uploading a 'folder' should work, too.
When ALL else fails...I've been known to read manuals, help files, etc. But ONLY when all else fails.
Guess what I learned? The 'select folder' option ONLY works with Chrome. So I fired up Chrome, logged in on it to my phone via Airdroid, and was perfectly able to upload an entire directory plus subdirectories, with their hierarchies intact, onto my phone's SD card.
The moral of the story: Fire up Airdroid from Chrome and try again.