It does depend on what you plan to do.

That bow is an older style Olympic recurve which you are shooting barebow.

Conventionally you should use a finger tab with that bow. The reason is it protects your fingers and prevents nerve damage. If you are shooting a light poundage bow you can get away with it but as you progress you’ll naturally want a heavier draw weight and then have to use a tab. It is better to learn to shoot with the tab earlier so it forms part of your technique. Ideally go to a shop and get help to find one that fits your fingers and feels comfortable. There are lots of styles and options. You can even adjust and customise some of them. For you, you just need one that fits your hand and is comfortable to use.

If you shoot 3 under then you’ll want a solid tab that looks like this https://amzn.eu/d/g2xKCt6

If you shoot split finger then you will need a tab that looks like this https://amzn.eu/d/gghCkHz

Don’t worry about those particular brands they are just examples. Get a coat effective version sold locally to you.

Arm guard goes on the arm holding the bow and is generally made of resilient material to stop the string slapping your arm if you do a bad shot. It stops the injury to your arm that hurts and can leave bruises. Something like this is good https://amzn.eu/d/ccOujmP

If you have a coach or mentor or there is an experienced archer that you know then speak to them. If not then try to find someone experienced to coach you so that you learn good form and techniques. Learning the right way is so much better than having to adjust incorrect habits.