I'd absolutely suggest M365 for this use case. If you set things up correctly (and that would be using Teams to manage SharePoint so that it appears as "just another folder" in File Explorer) you can get everything you say you need and more.
M365 handles collaboration on the same data files very, very well, including allowing simultaneous editing and merging the results. Heaven knows starting at $12.50/month for M365 Business Standard you're going to be hard pressed to get anything cheaper or better that gets everything they need plus more.
Was just tweaking the tenant for my client that's got a tenant with 2 seats of M365 Business Standard and 3 more of Business Basic this morning.
Another member gave me instructions for getting SharePoint into File Explorer for end users and being managed via Teams, which is the easiest configuration in a situation such as yours. You can download it here:
Integrating SharePoint Storage Into File Explorer for M365 Business Users.docx
Text is below, but there's also a screenshot in the source file that makes the narrative clearer.
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Getting the SharePoint Storage Into File Explorer for M365 Business Users
by Brian Mayo (
with modifications by Brian Vogel)
Getting the “blue skyscraper” representing SharePoint storage pinned into File Explorer is a step you perform manually. It can be automated, but for small clients with very few seats it’s just as easy to get SharePoint storage pinned into File Explorer by hand.
First...you need to have OneDrive signed in and syncing the user to their M365 account because OneDrive also drives the Teams (Sharepoint) file sync.
While signed in as the user, launch the Teams app. Click on the Team you previously created and to which you assigned all users who will be using SharePoint for file sharing. Click on the
General channel (or additional channel that you made) and then the
Files tab, then look for the
Sync button. If you are viewing on a wide screen monitor then if Teams is stretched out it will show, otherwise, click the ellipsis/more [. . .] button to the right to reveal the
Sync button. Click
Sync and you’ll see the sync happen and find the blue skyscraper pinned into File Explorer. You can also right click on that icon in File Explorer then choose
Send to -> Desktop (create shortcut) from the context menu to create a direct desktop shortcut to the SharePoint storage for the user. That can also be pinned to the taskbar and/or Start Menu for maximum ease of access from anywhere.