There are also "computation servers". Some of these are quite substantial machines. Their specifications are described at https://support.cs.toronto.edu/systems/linuxcompute.html . Some of them can be logged in to at any time; others are allocated with a "job scheduling" system so that you can have sole use of a powerful machine. All is described on that web page.
Please restrict your use of the apps machines to interactive, low-cpu-using applications. Computationally-intensive and/or long-running processes should be run on the comps machines, because they have more CPU power and because they are used less interactively.
You must read your CSLab e-mail regularly, either at CSLab or by forwarding it to somewhere you do read. I wrote a web page all about that.
If you are a TA for a teach.cs-using course, you will get a separate TA account at the instructional computing facility. These accounts' names begin with a 't' and then a digit indicating the year it was created; so your TA account probably begins "t3".
Teaching Labs passwords can be set or reset via https://www.teach.cs.toronto.edu/account (TA and student accounts only)
We've been doing computing and computer accounts much longer than the central U of T IT folks, so we mostly continue to do things our own way. Often our way of doing things is superior, at least for research computing purposes.
I suggest forwarding your firstname.lastname@mail.utoronto.ca e-mail to your CSLab account. But one way or another, definitely do read it too, because you will get notices there from SGS.