Presumably at aged 18 our young man was drafted into the Reichsarbeitsdienst.
From June 1935 it was made compulsory for every 18-25 year old to do national service, six months in the Reichsarbeitsdienst (the Reich Labour Service) then two years in one of the branches of the Wehrmacht. From the writing on the rear of the picture I would say the pictures are from around 1936.
Clearly our young man went into the Reichsarbeitsdienst, the exact unit should be able to be figured out by the arm patches you can clearly see in pictures 13_03 and 18_03. Picture 13_02 shows the Reichsarbeitsdienst building somewhere, on the reverse the only thing I can understand is R.A.D. The acronym for the Reichsarbeitsdienst.
The pre-war Reichsarbeitsdienst was based at a specific camp location from which its members would train, drill, practice, and take part in the various labor projects their unit was assigned to. Each camp and its Abteilung were given a number designation listed along with its higher Arbeitsgruppen number. These two numbers were often displayed together on the ubiquitous RAD Dienststellenabzeichen, an arm badge in the shape of a downward pointing shovel blade worn on the upper left shoulder of all uniforms and great coats worn by all personnel. The “front-line” rank and file members who made up the bulk of the RAD work force were armed with spades and transported by bicycles.
The big question is what unit of the group in the Reichsarbeitsdienst are the pictures of? Picture 18_03 would appear to read 70 over 6 and 13_03 would appear to read 153 over the number 2.
I wonder if the records exist of the unit members around 1936?
A note on naming of the pictures the first number is the page in the album and the second is the place on that page, an R at the end is the reverse side of a picture. So 18_03R would be page 18, picture 3 and the reverse of 18_03.