Gets all users from your directory in Atlassian. Related documentation https://developer.atlassian.com/cloud/admin/user-provisioning/rest/api-group-users/#api-scim-directory-directoryid-users-get.

Get-AtlassianScimUsers.ps1

function Get-AtlassianScimUsers {
    [CmdletBinding()]
    Param (
        [Parameter(Mandatory)]
        [string]$DirectoryId
        ,
        [Parameter(Mandatory)]
        [string]$Token
    )
    $startIndex = 1
    $totalResults = 2
    while ($startIndex -lt $totalResults) {
        $results = Invoke-RestMethod -Method GET -Uri "https://api.atlassian.com/scim/directory/$($DirectoryId)/Users?startIndex=$($startIndex)" -Headers @{Authorization = "Bearer $Token"; Accept = 'application/json'; 'Content-Type' = 'application/json';} -ErrorAction Stop
        $results.Resources
        $totalResults = $results.totalResults
        $startIndex += $results.itemsPerPage
    }
}
[PSObject[]]$all = Get-AtlassianScimUsers -DirectoryId $myDirectoryId -Token $myToken
$all | Measure-Object