Would like help choosing (free) remote collaboration software

I have a need - with almost trivial requirements - for some collaboration software. I know almost nothing about such products, and descriptions I've seen tout features far beyond what I need while failing to describe very basic features.

I have less than 50MB of data - mostly small (20-50KB) HTML files - that needs to be accessible and modifiable by one or two other people in a small non-profit organization.

Here's a list of requirements (or preferences) in no particular order.

1. The data will be accessed for several hours once or twice a week. There is no need for continuous access. This implies we should be able to sign in and out as needed.
2. Sign-in credentials should not be tied to the user's computer account credentials.
3. There will probably need to be access from both Windows and Mac.
4. There will be no need for multiple people to access the data at the same time, but the system should probably allow this. There should be some facility to lock a file being edited. (Hopefully that would be automatic.)

I use Box and gave Box Drive a try. It was OK but the sign-in process is cumbersome. It uses an email address for the sign-in id and there is no way to pre-populate its sign-in data. (I wouldn't necessarily want the password filled in, but having the last used email address - or better yet, a pull-down list of addresses) would be nice.

I tried looking at Box Sync, but could not get it to work. I think it requires a paid Box account; it won't work with my free one.

I will look into DropBox and Google Drive but I would appreciate comments on how well they would fit my very modest needs.

Does Microsoft's OneDrive fit in this arena at all?

Maybe I'm being mislead by "glossy brochure" descriptions of the product, but I don't see how Microsoft Teams Free is a solution to my needs. I need files either resident in the cloud but accessible on PCs (and possibly Macs), or resident on multiple computers and synched among them when they connect to some cloud service. The files need to be accessible by non-Microsoft software (an HTML editor, bulk email mailer, etc.), not my Microsoft Office software.

Google docs Google Docs: Free Online Documents for Personal Use

Regarding Google Docs, I'm once again limited by what I read in descriptions of the service. It sounds like Google Docs is a cloud based word processor with multiple built in document processors. All our editing (and other processing) will be done on one or more computers. We want the cloud to just provide either storage or a synching function.

Google Drive may be a solution but I don't think Google Docs is.

Kari said:

You asked what is the best collaboration tool, listing requirements. I suggested the best possible application / tool for you. It is of course up to you how to proceed.
Kari

I probably should not have used the word "collaboration" but I didn't know what else to call it. We will have a small number of people - 3 or 4 at most - that need access to a set of HTML files and a handful of csv text files. The files will be accessed by computer-resident (not cloud-based) programs. Only one person will likely be accessing the files at any one time, but any changes made need to be accessible by all.

There is no need for chat, video conferencing, etc. - just coordinated file sharing.