If you want to create an MLM chain using the Affiliate link then Follow the below steps.

Before New User Register MLM chain of Admin.

As You can see that Affiliate Test1 is registered under the Admin Affiliate chain.

STEP 1:-

To Activate the Referral code, Go to Admin Panel and select the referral code as a signup bonus up type.

STEP 2:- 
Goto Affiliate Dashboard copy the Referral Code, you will get the referral code in the payout section in the Affiliate dashboard as shown in the below Image.

STEP 3:-

When any user uses your referral code at the time of registration then it will look like as shown in the below image.

After pressing the Register button user is successfully registered on your site.

STEP 4:-

After Press on the register button, a user is registered, and to become an affiliate of the site and come under an affiliated chain user has to Login and press on becoming an affiliate button below Image appears after the user Login.

When the user Press on to become an affiliate Button A success message

After Successful becoming an affiliate user is able to see the affiliate Dashboard.

In the Above Example, Test2 Register through Admin Affiliate Referral Code So Test will go under the Admin Affiliate chain as shown below Image.
The chain creates after the user registers using Admin Referral Code.