If you’re considering buying Minecraft on your preferred platform, this is the optimum way to experience the game a little and know for sure before you spend your money. Whilst the restriction can be frustrating, this is more than enough time to try out the various mechanics in the game, and familiarise yourself with the gameplay loop if you’re uncertain as to whether you’ll enjoy it. The time limit varies from platform to platform, but always averages out at around 90-100 minutes, equating to around 5 in-game days. To ensure this isn’t exploited, you have a time limit imposed once you begin the trial. The free trial (regardless of the Edition or your platform) is the full game as paying customers would experience it there is no barred content that will be inaccessible.
In terms of the Java Edition, which is available exclusively to Windows, Mac, and Linux, an additional set of links are available lower down on the same page, with specific instructions on how to download and install each respective version.