Running on the treadmill is not something we advice. This is not going to help your knees.
Go run outside. Get used to the hardness of the ground. This is going to help your knees during a steep descent during your trek.
We understand if it is raining heavily (like in Mumbai) or it is way too hot (like in Chennai), you can choose to run inside on a treadmill and upload the screenshot.
The Nike Run club app has a treadmill mode. You can record your run on this mode and upload the screenshot.
The target remains the same.