How to upload photos to an album Facebook from iphone

Look here -

https://www.facebook.com/help/214757948549570

You can only add to albums you've created or a shared album you're a contributor to. Live videos can't be added to an album.

Note: You can upload up to 1000 photos to an album.

To add photos or videos to an existing album:

1. Click your profile picture in the top right of Facebook, then click your profile name.
2. Click Photos.
3. Click Albums, then click the album you want to add to.
4. Click + Add to Album, then click Upload Photos or Videos.
5. Choose photos or videos to add, then click Open.
6. Click + Add to Album, then click Go to Album.

Your album's privacy settings determine who can see your post. You can't change a post's privacy without changing the privacy of the album.

Learn how to add photos to an album after you've posted them.