Engine needs compression to heat the air charge. It needs suitable fuel injected at the right time and correct spray pattern to distribute it in the combustion chamber. If that happens it will fire.
Repeating some of yours and Jens' thoughts plus a bit more.
Compression - may be too low. Could be caused by a number of things. Rings, valves (including COV) not properly seated. Compression ratio incorrect due to improper milling of head, wrong piston/head clearance, COV problem.
Fuel - this should be a gravity feed so there should be no leaks into the system unless the filter is blocked. Unlikely as you are getting full power (maximum requiredl fuel flow) and it would probably start OK anyway.
Timing - this will make a difference to starting and to running. Easy to check.
Spray pattern - Injector may be fitted wrong (extra seals fitted), pop pressure may be wrong, nozzle may be dirty or faulty. May even be the wrong nozzle.
Correct grade of fuel is required.
All that said, your problem is likely to be Indian innattention to squish (piston/head clearance). Easily checked by feeding soft solder wire through injector hole and gently turnig piston thru TDC, followed by measurement of flattened wire.
Questions like 'did you dismantle and check for casting sand in the engine before running it?' or 'did you just run it as it arrived?' come to mind.
The answer to either could get your name changed to 'completely crazy' or 'damned lucky' from quite a few on the forum if your answers were 'no' and 'yes'!
Your supplier should be attending to problems like this. This is obviuosly not advertised as a 'CS'?. If it is, it is patently not, and you have been scammed, fiddled or just cheated if they give no warranty as to goods being fit for purpose. If the after-sales service is not forthcoming, let everybody know so they can avoid this make when making future purchases.
You wuld not accept that sort of thing if you bought a new car, so why should you accept it with a new engine?
Regards, RAB