My cousin gifted me the Monster Manual 2014 edition digitally and i redeemed it, it says on my account that i own the license for it and that i own the book but for some reason whenever i go to my character creation sheet on d&d beyond none of the species from that book that he bought show up under the species tab, he bought the book for the sole purpose of me being able to create my character with a certain species but now hes down 30$ and i cant do anything with it.

The Monster Manual (MM) does NOT give the player species options. MM contains statblocks intended for GMs to use as NPCs. It is generally not intended for use by players. If you want access to species as player options, PHB (2014), PHB (2024), and MP:MOTM would give you the most options. Other source books and adventure books will sometimes have additional species too.

I assume you and your cousin are new to D&D. I strongly discourage spending money on this hobby until you have finished at least one or two campaigns. Do NOT spend money on D&D until you are sure this hobby is for you. Additionally, please familiarize yourself with all the different physical and digital tools so you can make a more informed purchase. Physical tools includes, but are not limited to, pen and paper, dice, books, minis, play mats, cards. For official digital tool sets, there is D&D Beyond, Roll20, Fantasy Grounds, and Foundry. I strongly recommend checking out Roll20, Fantasy Grounds, and Foundry to see if they fit your needs better than Beyond. Roll20, Fantasy Grounds, and Foundry are better options than Beyond if you plan to dive deep into the hobby, as they have capabilities and features that Beyond severely lack. If you want access to all the official D&D content, I would avoid Foundry as they have very few D&D books on their platform.

If you are primarily a player, there is generally no expectation for players to spend a penny on this hobby. GMs generally provide all the stuff their players need. It is a nice and very appreciated gesture for players to chip in financially to help their GMs, but it is not required nor expected. If players do spend money, their first purchases would generally be a mini representing their character and/or the Player's Handbook (PHB).

If you want to be a GM, the MM is nice to have, but it is not necessary in my opinion. Basic Rules/Standard Reference Document/Free Rules (BR/SRD/FR) provides enough variety of monsters for free, and you can look online for homebrew monsters if you need more. As a GM, if you have the financial means to do so, your first purchase would be the PHB. If you are not in a position to make purchases, you can still provide all the materials for your players for little to no cost: join your local and online D&D communities and ASK established GMs for help to give you access to content. The D&D community is pretty generous; a lot of GMs spent hundreds of dollars on this hobby so you do not have to.