[Bender]

A tiny VM with the disk space to fit your needs using only OpenSSH + NGinx with autoindex enabled should suffice. Enable basic authentication on NGinx. Upload files via SFTP. Directories for your documents, tax records, photos, to-do lists. That's pretty much it. If family members need to upload files there are SFTP clients with a UI. Simple instructions with screenshots should suffice to get them going.

If you are not behind CG-NAT this can also be done from your home connection if it has the speed required to meet your family needs.