Yes, you can have as many users as you have phones… as long as they all log into the same account, they will all have the same simultaneous access/control to the projects.
What is this “generic link” you mention? How can we have many issues with something we don’t know about
No… I meant by simply logging in with the same account credentials on each phone/tablet. NOTE this gives everyone same access to all projects, but one solution is to make a dedicated account for that one project and teach everyone to never go into the editing mode To do that, you can clone your working project (after all the testing, etc) over to the other “multi-user” account.
Sharing is a totally different beast… I do not recall the guest user limits there, but the guest users can only connect when the master project is active and you do not have individual control over who can or cannot connect, the QR that you hand out is all or none… e.g. you can refresh it (AKA Generate New Link) if you need to kick someone off, but then you need to provide the new QR to all the remaining users.
There are perhaps some other limitations, but basically it works for what is was designed to do… share or demo your project in a limited fashion.
BTW, there are no real issues with the Generate Link function of the sharing… just some awareness issues with the cost and the misleading messages in reference to such… read through this topic for more info