Attach icon missing in Chat

Hi!

I started making my thesis last month and my supervisor suggested me to communicate trough Microsoft Teams but I have a problem with attaching files. He added me to a team, which I can see in the "teams" tab, where everything seems to work fine, but in the "chat" tab, where I speak only with him, it seems that I have kind of a "lite" version of the app because I miss the attach button and the software doesn't let me drag and drop. More awkward is that he can send me files and everywhere I look for help it says "simply click the attach button and choose upload from One drive or from your computer bla bla bla...". The same happens in Windows, linux, and the web version, so I infere that it should be something regarding my account.

Does anyone has an idea if is it there some configuration or something that I'm missing?

PS: I don't know if it's related to it, but maybe this extra info helps. In the Chat it's also missing the "Meet now" button, which I don't need, but it's also missing. Finally, when I click the "Add cloud storage" button in the "files" tab, it only shows the possibility to add an "Egnyte" account but not a one drive account.

I don't need those functionalities, but I would really need your help to find the way of uploading files in the Chat.