The Micollab clients location is included in the welcome email or the deployment email as long as the email template has been editied by the installer to include the link
You can also download it direct from your Micollab server
The Legacy app (version 7.3 and below) is available from https://FQDN/ucs/dl/UnifiedCommunicatorAdvanced.msi (CaSe SeNsItIve)
The Next Gen app (version 8.0 and above) is available from https://FQDN/ucs/dl/micollab_pc.msi (CaSe SeNsItIve)
Skype for business plugin – https://FQDN/ucs/dl/MitelMivoiceForLync.msi (CaSe SeNsItIve)