Mac Workspace error "This store doesn't exist. Please retry or contact support"

After plugging-in Gateway URL on Mac Workspace and entering credentials, Workspace prompt error "This store doesn't exist. Please retry or contact support"...

Unable to add gateway URL to the Workspace app. Your account cannot be added using this server addre

Account Adding failure in Citrix Workspace via inputing Gateway FQDN with below error: "Unable to add gateway URL to the Workspace app. Your account cannot be added using this server address. Make sure you entered it correctly. You may need to enter your email address instead."...