I am making a SharePoint team site for my company department in SharePoint Online. The department consists of 5 units, each of which have been given a document library to use freely and only by that specific unit. For this matter, I have created 5 SharePoint groups that I have assigned access permissions to the corresponding library for - this means that each document library has unique access permissions, not inheriting from the parent (the site). All 5 groups do also have access to the parent site, which will be used for department-wide information. I am fine with assigning each employee to their respective group manually, as I only need to do it once per employee.
My department also provides documents that the entire company needs access to, including the employees in my department. I have made a document library also for this purpose, and created a guest group for which access can be requested and automatically accepted. This guest group, along with the 5 groups belonging to the department units, have access to the "public" document library. My issue is that when I share the public document library via link, a "request access"-screen appears that sends the owner (me) an email to accept or deny the request - this request is for the document library itself, not the group. Not using a guest group is in itself fine, but due to the amount of people that will be accessing this library I need the functionality of automatically accepting requests. Hence, I need the links I send out, and that can be used to send automatically accepted access request, to be for the group and not the library. I have looked but I am yet unable to find it: How do I send a link to the actual group itself, where the employee can request access?
If it is not possible; Is it possible to auto-accept access requests for a document library?
And a third question on the topic: Is using one document library per unit the best way of doing it? According to several online sources, different libraries is better than just creating one library and splitting the documents over several folders with different access permissions.