1) Your Facebook accounts age must be 18 years or above. If it's not change your birthdate on Facebook.
2) You must turn Facebook followers in your facebook setting, change post privacy to PUBLIC from here. (example)
3) Change your post privacy to PUBLIC. (example)
1) Click the login button on the homepage.
2) Fill in your credentials.
3) You'll be taken on a page where you'll see a yellow box. Copy all its content (Desktop: Right-click > Select All then Right-click > Copy) (Mobile: Touch and hold your finger over the text in the yellow box. Soon an option of Select All will pop-up click it and touch and hold again and then click the Copy option) and paste it in the box below the yellow box and click submit.
4) Choose if you want likes or reactions and proceed accordingly.
1) Go to the post you want likes on.
2) Below the name of the person who posted the post there will be a text in gray (the date and time) right-click on it and then Copy Link Address (make sure the post is public).
3) The URL you copied above is your post URL. Paste it in the "Post URL" box.
Note: you can't fill Post URL and Post ID at once. You have to fill either of them.
4) Finding Post ID is a more complicated task and it would be better if newbie's do not use it.