> I don't know how people managed without being able to use translation apps, for example.

I learned English with no Internet or smartphones, just school teachers, coursebooks and physical dictionaries. I wrote down new words from the dictionary into my lined notebook with a pen, solved the exercises from the book, translated texts by looking up words in the dictionary, searching for the page and the entry alphabetically. The coursebook came with an audio cassette. It was very much possible, but of course there are much more tools today. Spaced repetition software like Anki for vocabulary learning is a huge improvement I think.