I have encountered this problem, so I will. We can choose to add address book friends, and we can do this in a small circle. I put the methods and steps below.

1. Log in to your Pinduoduo account, open the home page of Pinduoduo, and click the small circle to enter:

2. After entering the small circle, click on the avatar in the upper right corner to enter:

3. We can choose to scan, add friends, or choose friends in the address book. The following is an example of friends added to the address book:

4. After entering the address book page, we click Add on the right:

Next, just wait for your friend's consent and you can successfully add your friend.

In this way, Pinduoduo friends were successfully added. If you have other methods, please leave a message in the comments section below.