how to resize the large canvas when open customers file ?

i got two question  :

1. how can save the file ( pdf ) is actual size ? cause when the file make in a large canvas over 500cm , but the client made the artwork in normal size (43.7x57.4cm) ,  when i open the artwork in PS , it will follow the larger canvas , the artwork will smaller 10x times , it will show( 4.37x5.74cm)cm ! 

how to fix it ? 

2.when i copy the artwork from a large canvas file , i place in a new doc which is normal artboard size

but the artwork size was changed ! 

please check the image , when i open the file  in AI / PS 

first photo : open in AI (OG)

second photo : open the file in PS ( size was smaller than 10 times)

third photo : copy the OG file in a new open doc . 

fourth photo : the artwork size was different

did anyone face this problem ? and how to fix it ? 

thanks all