Can I use TeX (LaTex) with AnkiApp?

Yes. To use TeX mathematical typesetting in a deck, you will need to either create a new deck with a custom layout, or add a new layout to an existing deck (See https://ankiapp.freshdesk.com/solution/articles/5000623420-what-are-layouts- for instructions on how to manipulate layouts).

First, choose the field that you wish to be treated as TeX (in the screenshot below, we're using the "back" field). Next, edit the layout, so that that field is contained within an HTML element that has the attribute "data-type='tex'".

Now, content entered into that field will be displayed as math.