Stems stretching and pitching

i have a problem, or dont know if its a problem, maybe i didnt learn about it well but i cant find it anywhere…
So my problem is when i get stems for collab from someone and i will put it to my project they are stretched so i will time stretch it to fit them to bars but its a bit pitched sometimes is quality destroyed because of that, could you please help me how to solve this? maybe some advice what should be turned off or turned on, or some tutorial for this?
Thank you


Do you use the same sample rate in the project as the sample rate of the files is? If not, do you resample the files while import?