Anchor or root X509 - and also entourage

[René v Amerongen]

Hello,

I try, for several users, to get entourage work with an exchange server.

If I download a crt file from
http://www.instantssl.com/ssl-certificate-support/cert_installation/
specially the file
http://www.instantssl.com/ssl-certificate-support/cert_installation/ 
ComodoSecurityServicesCA2018.crt

Then I do convert it to pem base64 using the MS cert-Manager.app  
requested for using the entourage exchange connection.

But when I double click the new file I get of course keyChain access  
and want to add it as an anchor-x509.

This works if I am root, but not when I am a normal user. Then I  
don't get that option.
Also when I do it with root, it shows up as anchor, but when I check  
with a non admin user account I see it as a root-x509.
( btw I don't see them in the list of certificates, but I do when I  
use the search field )

Who or what is wrong? Also why is still entourage saying it is the  
wrong cert.
The window users have no problems with that crt.

Any help or even a verification that this should works would be great.

Thanks in advance,

René