The 2.1.5 version was for some time ago and newer, better, faster versions are available for FREE.
You should probably be able to use any SQLite Studio version to open the *.db files that you wish.
Keep in mind that it sometimes takes SQLite as long as 15 to 25 seconds to open a large database so BE PATIENT!
It is also recommended for opening custom .db files in Ultra Hal 7. Again, give it time to open them.
You need to learn your way around in the program but it's not too difficult. There are plenty of tutorials on YouTube and other sites.