What's important?

First of all, spelling is not the most important thing, comprehension is.  In everyday life, you need to be understood and to be able to understand (more or less).  A few errors here and there usually make no difference whatsoever. It also depends on your own circumstances.  If you’re affected by dyslexia or sight loss, or any number of conditions that make spelling or reading difficult, then that’s a totally different situation.

But generally speaking, spelling is usually important when you’re trying to get a job, for exam purposes, and for any kind of writing that is going to be read by someone else.  And without some kind of spelling rules, it could become a lot more difficult to understand any written text in any language.  To take an admittedly extreme example, maibea jookan reed dis mesidj djust as fahst if yoo ar a neitiv inglich speekar but if I spelled things how I liked, in my accent as I see it, and so did you, then language learning (and reading) could be a lot harder for everyone.

So depending on your reasons for learning English, whether you write a lot or not at all, and also on your own personal circumstances, spelling can be a vital part of comprehension... or indeed a not so important one.