Hi
Congratulations on joining. I am a new member too.
The machine in the photographs is a 15-91 so congratulations you have a very good sewing machine and you have the original instructions for using it.
Using online resources I would suggest that your machine was built in 1935. Bear in mind that however good your machine was or is she is now over 80 years old. That shouldn't mean too much to the cast iron and polished steel parts but the rubber insulation on the wiring is likely to have suffered from age and may make the machine unsafe to use. Please have the wiring, motor, light and controller checked for safety before you start using this machine and do follow the cleaning, oiling and greasing instructions.
Safety checked, clean and lubricated the 15-91 is a very good quality machine which will last a lifetime. It doesn't do anything complicated so is perfect for a beginner. It really depends what sort of sewing the new owner wants to do but for patchwork, straight line and free motion quilting, home decor and basic garment construction it should be perfect.
Hope the is helps. There is a ton of information on the internet that can help you get this very fine machine working well and above all safely.
Happy sewing
G