I will say that you can probably avoid the Relationships issue for some time and be OK.
I have created quite a number of non-trivial Access databases without paying any attention to the Relationships window whatsoever.
Of course, to handle integrity, I did so on the form level if needed - but I rarely if ever allow Deletes in the first place, much less a Parent delete.
Edit: I should add something. I am aware that, to many new developers (and maybe even to some expert developers), the Relationships feature is a chance, a way, a method whereby they.....mentally digest & even develop their concepts of the normalization of the database. It's where they prove the normalization level to be appropriate and sufficient. And that's totally fine. It's just that sometimes new developers get confused and seem to think that Relationships tool is as necessary as normalizing your data structure is. Because some people use them as a way of visualizing and proving their good data structure it gets confused as being part of that - but really it could have been a word document or a napkin, as long as it's done right. I say that, of course, without mention of referential integrity purposes--because I already commented on that, above.