Tripal 2.0a is an alpha release. We anticipate it may be buggy and appreciate feedback if you find any issues. We recommend that this version not be installed as future updates are available. However, if you would like to install the 2.0-alpha version, please follow the instructions in the Installation documentation for Tripal 2.0. However, when issuing the Drush command to download Tripal please use the following to retrieve the alpha version:
drush pm-download tripal 7.x-2.0-alpha
Also, you can download Tripal Extensions and install each as typical Drupal modules to extend the functionality of your Tripal site.
See the Tripal Tutorial for Installation Instructions.
Please Note: In previous version of Tripal there a Tripal theme was required. Tripal v2.0 no longer requires a separate Tripal theme but should work automatically when the default theme of the site.