Hello, if i use zwiftcog do i need only to use crankset or do i need complete groupset on a bike?
As with any single speed bike setup, you need some way to tension the chain.
If the bike has a thru-axle or vertical dropouts, you can use a chain tensioner in place of the rear derailleur if you want. Or you can use a rear derailleur as the chain tensioner. If the bike has horizontal dropouts, you may be able to use that to adjust chain tension, but bikes with horizontal dropouts are not very common today.
The Zwift Ride frame has a built-in chain tensioner.
You can find chain tensioners at online bike parts retailers, or ask your local bike shop.
So i can just use 1x10 crankset with deore Rear Derailleur and 1x10 chain if i understand?
Yes. That will work.
Yes that can work. If you don’t have a shifter, you may need a way to position the rear derailleur in line with the cog that requires more than simply adjusting the limit screws on the derailleur. For example you can take a short piece of an old derailleur cable (with the cable head on it) and feed it through the barrel adjuster of the derailleur, so the head of the cable sits in the barrel adjuster. Then push the derailleur approximately where it needs to be, tighten the cable anchor bolt, and do fine adjustment with the barrel adjuster. A piece of an old spoke can be used for that as well. In this way you are “shifting” the derailleur to where it needs to be, without using a shifter.
Blimey Paul.
That’s a level of detail that’s probably just blown the OP’s mind. 
Yea i will just leave everything at my local bike shop to adjust it for me 
I cba doing on my own.