C++ is a complex beast, some people have been writing it since age 10 on their own, some people learn it at the uni, some people never have any formal education.
Most large organizations tend to come up with style guides and use a subset of c++ in their day to day - doing anything outside of that subset is frowned upon. This is also a major point of contention for the language standard to move forward and why things like boost or abseil exist… to create a common subset and make it easier to mix and match code.
Which subset are you supposed to be learning, I don’t know. It would be good if you could practice writing running code in something like a text editor until you’re used to the syntax you’re expected to be using.
In eastern Europe, there’s this concept of a type of book called “collection of problems”, it’s kind of like a workbook you may remember for maths but for programming languages or algorithms and datastructures these are meant to drill down syntax into your fingers. First chapter for c++ would be called something like “input/output”, going through it, you’d be writing code for a hundred short programs that read stuff in, and write it out. Next chapter you’d have loops, next chapter you’d have functions, and so on. They tend to work mostly universally across programming languages as well. Your ta, would pick some of those problems out, and analyze in front of students what makes a particular solution good or bad.
I’m sure you’ll be able to find something similar to help you bootstrapped with the basics.
https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list will get you through the language feature stuff
My cousin did a CE degree whereas I did more of a CS/SwE , and I happened to do algorithms and datastructures more in depth. In for years at the uni, nobody ever explained to him or his friends what a ring buffer is, as trivial a datastructure as it is, it was expected he’d pick it up on his own in order to do stuff with it.
Beyond classes and templates and operators, you might need to understand roughly what maps and vectors are, and eventually if/when you get to concurrency (we had 4 semesters of it of subjects with different names) you might be expected to know the basics of how to use mutexes and queues and threads and callbacks end executors and futures. Won’t have to design your own, but in this day and age of 16c/32t Threadripper, it’s more than likely to come up.
Ask your colleagues what they’re doing, ask them whenever you have small concrete questions about stuff, exchange/get someone’s lecture notes, there’s always one super organized person who has great notes around, spend more time studying and practicing.