Build Remote Access to Files for Small Office

General information for the business: We are a small growing building and project management company of 4 departments (one employee per each department) + admin. We have our OneDrive system and use linked Excel files at the moment. We need an instant online remote access to preview, edit and save files. Kind of support: Network Description of support work: We are a small growing building and project management company of 4 departments (one employee per each department) + admin. We have our OneDrive system and use linked Excel files at the moment. We have 3 PCs and ipads. Unfortunately for OneDrive it does not allow to change Excel files remotely without downloading and saving up a copy of a document (which produces lots of copies and confuse). Also at office we cant edit / work the same files simultaneously. Also, our OneDrive disc is external that looses the paths frequently and as a result, synchronizing. And, om top of that Excel does not work properly with the links via sharepoint. And information gets into references loss (screenshot is attached). So, we need instant reliable solution for remote work compatible with ipads, Excel and SQL for example, could be HTP server a solution with a separate another PC or any other alternative. Extra notes: