Downloading File(s) on iPhone
Select the menu icon (three lines) in the upper-left corner.
Select Accounts or Contacts (depending on where the file is).
Search for the Account and select the desired option.
If searching by Contact, use the Sorting and Filtering options from the Files page.
Select Files.
Select the File you want to download.
Select the ellipsis (three dots) in the upper-right corner.
Select the Download icon.
The file will now be stored in the Files App on your iPhone.