Cannot reinstall OS X. Will Apple Store do it on the spot? I installed Windows on my MacBook Air 2015 and erased the SSD in the process because it's only 128 GB and because I thought it would be easy to create a bootable USB key to reinstall OS X should I need to do that.

I then found out that power management under Windows is lacklustre to say the least. Right after that I had to realize that creating a bootable USB key from Windows is difficult to say the least requiring (paid) third party software. What is most strange though is how difficult it is to get the actual file from a Windows PC. I had to download one for OS X El Capitan from a shady website.

The stick I created with TransMac did not show up as a boot option even though I made sure it was formatted the right way (as per an online guide). Internet Recovery gives me error "-4403F" which Google doesn't seem to know.

So I'm stuck.

My question is if any Apple Store (I'm in Germany now but will be in Thailand next week) will reinstall OS X for me on the spot (as I would think they'd do) if I just walk in with my laptop?
On startup hold Command+Option+R. You can now use Internet Recovery to install OS X. Don't download from shady sites. You are compromising your security this way.