flash – Meike MK-910 + Nikon D3300

I have a Nikon D3300 camera and I decided to take a step forward: buy an external flash. As I have a very tight budget, I would opt for the SB-100 "alternative" – ​​Meike MK-910.
My question is whether the flash and the body are compatible in two ways;

a) is ttl communication reliable?

b) how to use the flash outside the camera (as a slave). Does it work directly or do I have to buy a transmitter / receiver?

Thank you.