Hello RobKites,
Thank-you for your questions.
Basically it is not a must to download and install a new ZAPTEST version but it is highly recommended because of the following reasons:
1. Although Zap continue to support all its customers and their different ZAPTEST versions, but the official ZAPTEST support is only on the newest version.
2. The new ZAPTEST versions are improved and more robust, their improved features include such as new GUI, new and improved methods, more useful functionality, much higher performance, etc.
3. The installation of the new versions is simple just as the old versions, and do not damage any of the already created testing scripts.
4. The entire ZAPTEST features are summarized in the ZAPTEST Readme file and can be found as simple explained videos in the Zap portal -> User Zone (Which every ZAPTEST user can request access to it).
Please contact Zap for further help.
Thanks,
Sasha