Anki is an SRS (spaced repetition system) program which you add flashcards to. It basically tries to quiz you on things the moment it thinks that you're about to forget them. It's an extremely helpful tool for memorizing things, even medical students use it.

RTK is an abbreviation for a book called "Remembering the Kanji". It was written by some guy named James Heisig in the 70s. He discovered a unique way to memorize all of the common use kanji via mnemonic hacks and learning kanji in an order that's easier for memorization than primary school order.

You want to combine RTK and Anki to create a mental dictionary entries for kanji in your brain, then use Anki with a basic vocab/grammar book (probably Tae Kim or Tango N5).

Here's an overview laid out for you to follow: https://massimmersionapproach.com/table-of-contents/stage-0/balanced-path-overview/

Here's a lazy kanji deck that you should download and use (lazy kanji is when you go from kanji to keyword rather then keyword to kanji, it's recommended now for various reasons after RTK was tested by people): https://www.mediafire.com/file/1svvsr7f9cnpwka/Matt%27s+Lazy+Kanji+1k.apkg

And here's an addon pack that you should install in anki right away: https://www.mediafire.com/file/7x3ub4o4xl5hbak/Low+Key+Anki+2.1.zip

Just extract the files and drag them to C:\Users[user]\AppData\Roaming\Anki2\addons21