I am trying to work out how i can manage a subset of users in Office 365. We have 20.000 Mailboxes in Office 365 and i need to only manage 600 from the UK.

Basically i need to run something like Set-Mailbox -CalendarRepairDisabled $true but not for all mailboxes.

I have tried to see if i can use something like -filter '(company -eq "COMPANY")' but that did not work. Then i thought of running through members in a group and do it that way but i was unable to do:

Get-ADGroupMember -identity "GROUP" | set-mailbox -CalendarRepairDisabled $true.

We are in a hybrid setup with OnPrem Exchange 2010 servers.

Thx in ad

You need to create a RBAC role for managing the commands.

if those users are in separate OU, you can create recipient filter scope and assign the scope to RBAC group 

Do you have a source that explain the RBAC model? I have looked into it a little bit but need more time to get my head around it.

THE OU option does that work in a hybrid environment?

If OU option is not an option then

you can filter for users on  basis on company / country value , then add them to DL and set the command  set-mailbox -CalendarRepairDisabled $true for that DL group members.