Most of the Facebook users now prefer adding Photo Albums of the events rather than adding single photos to their accounts, This is the most popular and easy way to share unlimited numbers of photos online. If you come across such huge albums and you want to download all those photos in the album you need to follow these steps.
First of all I prefer you to choose Google Chrome browser as it is quite easy to download Facebook Album with the help of some 3rd party extensions available for the Chrome browser.
First of all go to Google Chrome store and download and install the PhotoLive Chrome extension to your chrome browser, or you can simply download it from its original website. 
Now open your Facebook account and navigate to the album you want to download. You will find the Blue “Download Album” button on the top left side of your window. If it didn’t appear yet we recommend to reset your Chrome browser.
This will take you back to the original PhotoLive site. Which will prepare a PhotoLive, Photo Live, Download facebook album, download facebook album zip file, Facebook album in zip file.for all your photos in the given album for download but it will work in background.
After the ZIP file is composed it will automatically start Downloading your Photos in a single ZIP file format. When download finishes open your ZIP file and extract it wherever you like and you will have all those specific Facebook Album photos saved to your PC or MAC.
NOTE: if you don’t find the download button on certain Facebook albums , this is most likely that the page or Profile owner has set limited photo permissions. You can contact that person and ask him/her to make albums downloadable.