Share spreadsheet for collaboration
From the listing page
Tap ... right next to the name of the spreadsheet that you want to share
From the contextual menu that appears, choose Add People
Enter the email addresses of the people you want to share the spreadsheet with, then choose the level of access you want them to have.
From the spreadsheet editor:
Tap Add People icon in the top-right corner.
Enter the email addresses of the people you want to share the spreadsheet with, and choose the level of access you want them to have.
Alternatively, you can tap ... > Collaborators > +.