If the contact did not receive the share email, then resend the email for a selected file. The re-send email will point the contact to the project portal which will contain all the files they have been shared for the project to view or download. Re-send the share email for a file by:
Go to: Project > Documents tab.
Locate the folder that contains the shared file.
Select the row action button > choose the 're-send share email' option.
Type a message to send to all the contacts (and internal staff) that the file is currently shared with.
Click send.