I didn't know Digital Ocean before, but it seems like they are more focused on CPU than on disk space. This is bad, since you will need to store some data on the server, if you send any images at all. We have a matrix-server running for 4 people since maybe 2019 and it's at 60gb disk usage right now. So in that regard, 10 memers will need at least a 100gb so 24$ a month, but you can get a lot cheaper than that, using some other server hosters, which are more focused on giving you a lot of space instead.

Specs: The server we use has 4 cores (barely uses 1) and 8 gigs of RAM, 2.5 of which are currently used and 120gb of disk space, that will probably suffice for another 2-3 years.

You can always mount in an S3 bucket and use that instead of the local drive.

Hi, I been running Conduit in a "Allways free" droplet at Oracle Cloud.

Its been working without problems for a single user setup (no VoIP though).

I hope you get an idea of the minimum resources needed.

Matrix does not need much resources per user or room But if any user joins a large room with thousands of people, the server will need to keep up with all those state events.

So 100s of users wouldn't be much of an issue if they're mostly in the same room.