For Scalix 11.4.5, any edition of Scalix, including Scalix Community Edition, can be used. Scalix Connect for BES 1.0 will cease to work with Scalix 11.4.5 on 2009-12-31. You will have to upgrade your Scalix Server to Scalix 11.4.6 or higher before that date. Note: Scalix 11.4.6 will be released in Q4/2009.
You can read that in the release notes