How many days Google takes to crawl Referlink and Backlink

I have the same question actually, I created some backlinks but in my SEO tools, they don't seem to appear, how long does it take for Google to spot them?

Depends on the site they are linking from. Could be quick like 24 hours and sometimes it takes much more time - specially for smaller sites with lower update frequency. Google typically crawls those websites less often and therefore link discovery takes more time.

How it is in SEO, it depends. Unfortunately, I recommend you be patient.

It takes zero days. The very same day it get crawled and within 3 days it gets reflected in the Links section of Google Search Console.

Change in link on a webpage force Google to crawl the page at the earliest.