can this 20 user limit be bypassed somehow? if the software is under MPL, does that allow restricting functionality in the software like the user limit imposed here?

How has your experience been than an installed libreoffice? I have this thing where like 5-7 users have to work on a network share drive on "xls" files. For over 15 years now we have worked on this setup whereby everyone knows the folder structure, the naming scheme among other things. I want to try this browser thing for "collaborative editing" which isnt present in excel or libreoffice desktop but i fail to understand how i can manage this.

do i have to map the network drive over to the browser engine? do i open the network drive as always and double click the file to run in browser?