What happens when you order
You put your link in the box and press the button. The next screen opens with it already filled in. You choose how many followers you want, pay, and the order starts after that.
Where to find it
Go to the profile or page, tap the three dots next to Edit, and choose Copy link. On a laptop, copy what's in the address bar.
Check this first
Set the post or profile to Public first. Anything limited to Friends is invisible to the accounts sending the engagement.
Why order Facebook followers
Personal profiles have following switched off by default. Go to Settings, then Followers and public content, and set who can follow you to Public. Pages don't need this. The old auto friend requester is retired for good, it sent requests from your account and that was what got people restricted.