You will need to add/update the Calendar permission entry on each member of the team. Something like this:
Add-MailboxFolderPermission alexW:\Calendar -User LeeG -AccessRights LimitedDetails
Rinse and repeat for each user, and be mindful that the name of the Calendar folder might be localized (for any non-English speakers).
If an entry already exists, you will need to use Set-MailboxFolderPermission instead. Refer to the cmdlet help for more info: https://learn.microsoft.com/en-us/powershell/module/exchange/add-mailboxfolderpermission?view=exchange-ps