Once that's installed, go to the revanced app and go to the "patcher" menu.
Click "select an application" button and then click the "Storage" button you see on the bottom. Then find the youtube APK that you downloaded and click it.
You can now select the patches you'd want the app to have. You could just select "default" to have it patch the 52 or 57 things that most people care to change.
Now just click the patch button and it'll hopefully not fail.
Hope that looks good formatted. I'm on my phone lol.
You should try and keep the sponsorblock patch added. You can just have it show a "skip" button on the sponsored ads in the videos and it'll skip past it all. It's a pretty useful thing to have. You get to also see the different marked spots on the scroll bar.