i think it is F8, but it have round on doors, do you know, what is it? Thank for your time!
As a 1938 car, it's too early to be an F8.
My best guess is that it's an F7 Meisterklasse Saloon (hence the 690 cubic centimeter rating on the plate).
I'm not sure what you mean by radiun on doors but bear in mind that as an 80 year old vehicle, the chances of components having been added or removed are far greater than a more recent car.
More info on the DKW F7 is available here
It's a DKW F-7 - it can't be an F-5 as they had stopped production by then, and it can't be the F-8 as they weren't made until 1939.
DKW was part of the Auto Union AG Group which at the time was a group consisting of four separate brands (Audi, Horch, DKW, Wanderer), so while the logo in the fourth picture appears to modern eyes as the Audi logo, it's not. The Auto Union logo was four rings to represent the interlocking of the four companies. Following WWII the displaced execs of the original Auto Union AG formed Auto Union GmbH which spent the next few decades transitioning into the Audi of today.