Albizia can work as bonsai, Spongeman was giving you the ''straight poop'', it is not an ''easy'' tree to do well because it needs full sun and does indeed drop branches easily. Spongeman has a number of Albizia bonsai, he is sharing hands on experience.
It is possible to grow a great many trees under lights, but trees that need full sun are difficult. Visit your local ''Brew & Grow'', or Hydroponics shop to see grow light systems in operation. You can then order on line once you know what light system you want. A tree that needs full sun wants as much light as a marijuana crop or a tomato plant. Grow shops will often use pepper plants as a stand in for marijuana as they need about the same light.
Your plant is a young seedling, as such can get by on slightly lower light, but will eventually get weaker and weaker and die if it does not get sufficient sunlight. As they age they need more light.
I suggest you try again with different species. that require shade, or partial sun, rather than a species that needs full sun.
For shade, indoors, probably the most adaptable is Ficus. Also Serissa, Bryna, and maybe a few others. Meehan's Miniatures has starter material at modest prices. Check for their indoor shade listings.