The free trial is a limited version of the Professional subscription. You can save three (3) Hashtag & Keyword trackers, and three (3) Account trackers.
There is a post limit of 5000 posts collected across all saved hashtag and keyword trackers, and once the limit is reached the trackers will stop pulling in posts. To continue tracking past the 5000 posts, you can upgrade your account here.
A free trial will not backfill data in your tracker. Any past posts shown in your tracker will be a sample of historical data, and not full historical data.
Features such as downloading and exporting data is a paid feature, and is not available through the free trial.