Documents by Readdle - A central hub for all your files.
Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
Documents Pro 7 - The ultimate all-in-one mobile office suite for the iPhone and iPad with 8 premium apps in 1.
Creativity 365 - Cross-device content creation suite
GoodReader - With GoodReader on your iPhone, iPod Touch or iPad, you can read virtually anything, anywhere.
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.