Box Icon not appearing as export option in "Photos" on iPhone for multiple photos

I need the Box Icon to show up as an export option in "photos" on iPhone (next to messages, mail, dropbox, etc). I do NOT want to use the box app because it takes the files in *.HEIC which is incompatible with everything. I need to be able to select *multiple* images in photos (it appears to work for a few photos but not many e.g 10+?) and then hit the share button and then hit the Box button (and then choose the folder, etc). 

As an FYI, Dropbox is able to do this but Box is not.

Thanks for your help.