I'm looking for a good, cheap, cloud-based document sharing system for a small NGO (30-40 employees) that allows us to easily save documents under multiple files/filters/tags. That is, each document has a 1) project name, 2) document type ("concept note," "policy memo," etc.), 3) sector ("health," "education"), 4) sub-sector ("maternal health", "child health"), and 5) country office. Google Drive is fine for organizing files under one folder-based hierarchy but is a bit unwieldy when multiple tags are needed - I want this to be as easy/automated as possible, both on the uploading end (ideally you would be automatically prompted to select tags of each type) and on the browsing end (simple to choose which structure to search or browse by).
The closest thing I've found so far is https://www.smartbins.net/, but smartbins doesn't seem to allow for nested folders (which they call "tag clouds") and the file upload feature isn't working on my browser anyway. It's also $10/user/month, and given that we don't require a huge amount of space I wonder if there are cheaper options.
Any recommendations? Thanks!