I am a tour director for a company that organizes trips for high school bands and choirs. I end up at WDW about 5-6 times a year with them.
First of all, not every company gives out pass numbers in advance. I believe more of them do so now, because of customer demand. Our policy, since the start of
MDE and advance FP+ reservations, is to send an email over 30 days in advance to the group members, letting them know their pass numbers. That way they can link their tickets to their MDE accounts. Of course, some of them have to create an MDE account first!
We do NOT distribute actual hard tickets until arrival the first day, to avoid "forgetfulness" or loss, but as long as the group members know their pass numbers, that is not a problem.
How will your group be touring in the parks? Almost all of our groups allow students to tour in small groups, usually at least 3-4 students per group. Trying to stay in very large groups is both cumbersome and inefficient.
What I personally recommend is that the students who want to tour together schedule a time to get together several weeks before the trip to discuss which attractions they want to experience together, so they know which FP+ they want to try to get. It is obviously VERY important that they know the group itinerary before making plans, to know which park which day, as well as any performance times, to avoid conflicts.
For example, I am taking a group the weekend after Thanksgiving. They have a workshop at Epcot on Saturday morning, then they will be in the MK the rest of the day, through Wishes. So they should make their FP+ for MK starting anytime after about 12:30. On Sunday, they march at Epcot late morning, then return to the park that afternoon, so they have afternoon/evening Epcot FP+.
If your group is doing the typical MK afternoon parade, they should make any FP+ that day before 11 or after 4.
I also advise that they can definitely LINK accounts with their touring group if they wish, as friends and family, but it is not vital that they do so. Some find that more confusing, so I just tell them as long as they find the same or overlapping FP+ times with their friends, they can enter the line together.
Let me know if you have any questions, I love my job!