Depending on your internal IT-service configuration you may need to whitelist Planday domains.
Here's our domains list:
*.planday.com
*.planday.dk
*.planday.net
*.punchclock.dk
dicgpsstbxaq4.cloudfront.net
planday-cdn-contractedhours.azureedge.net
planday-cdnfrontendfiles.azureedge.net
planday-cdn-reports.azureedge.net
planday-cdn-corehrintegration.azureedge.net
planday-cdn-applicationhost.azureedge.net
planday-cdn-punchclock.azureedge.net
planday-cdn-absence.azureedge.net