Non profit business standard users join PCs to Active directory

Hi I have waded through masses of online stuff and can't get a clear answer to this. It is driving me insane!

We have about 10 users on nonprofit business standard - all running win 10 or win 11 pro.

I need to allow different users to share a PC - but have user restricted access to microsoft 365 online data - sharepoint - web apps etc

Most older machines are domain aware as in you login with the domain account - they work fine.

Newer machines cannot and all have only local accounts but have stored credentials for the main user for sharepoint etc. That is a problem when a PC is shared as someone may have logged in locally but they have left credentials for sharepoint allowing access. to privileged info

If I upgrade one of the licenses to business premium would that enable me (with admin privs) to join existing and yet to be bought PCs to the domain or would I need a premium license for each user? We don;t need the higher up functionality such as intune as far as I know - just the ability for fred_AT_ourcharity.com to share a PC sensibly with bill_AT_ourcharity.com