In most cases, it's better to use link locker. If a user is welcomed with a content locker right after opening a website, it's most likely he/she will move on.
Increase conversion with this simple tip:
Password protect your file in a zip/rar archive and put a Read_me.txt file also containing information about how to get password.
Create a Password.txt fiel and upload it to the PPD network.
Grab file download link and put this link into the Read_me.txt.
Put a instant download link of the zip/rar file you created on your download page on your website.
This way the user who have downloaded your file will think he's just one step away from using the file he has downloaded.