Hey everyone,
I hope this helps someone in the future, or myself if i happen to forget how I fixed it.
I essentially followed these steps, even though i had already completed all of it in order to export an .apk in the first place and test on my phone up until wanting to get the app to the Play Store... so if you've also gotten your app to your android device already, you're likely just in need to create a custom build.
The first step is going to project > Install Android Build Template... and completing the process which does not take long. For quick access to the files that were created, just go right back to project > Install Android Build Template... and click Show in File Manager
You should be taken to the 'Android' folder that contains a 'build' folder and 2 other files.
go to build, and right-click on the config file (config.gradle) and open using notepad or notepad++ (or any text editor)
You should see this:
ext.versions = [
androidGradlePlugin : '3.4.2',
compileSdk : 28,
minSdk : 18,
targetSdk : 28,
buildTools : '28.0.0',
supportCoreUtils : '28.0.0'
]
For me the error I was getting was talking about the target API needing to be 29 rather than 28. So i changed it to this:
ext.versions = [
androidGradlePlugin : '3.4.2',
compileSdk : 29,
minSdk : 18,
targetSdk : 29,
buildTools : '29.0.2',
supportCoreUtils : '28.0.0'
]
NOTE: buildTools was set to that because in my directory containing my build-tools, the latest one was the 29 one.

Once that's done, you are close to creating a custom build. Go back to Godot, and go to Project > Export...
Find the section that has Use Custom build

If you can, go ahead and hit Export Project, Otherwise you have to go back to Editor > Editor Settings...
In your tabs on the left side, find the Android tab under the Export section. You must get the Custom Build Sdk Path. I honestly was not quite sure which one was right, but this worked for me (of course it is relative to my system, so yours will be different but might be similar.
C:/Users/xxx/AppData/Local/Android/Sdk
Again, for reference, this is what led me to the solution...
https://docs.godotengine.org/en/latest/getting_started/workflow/export/android_custom_build.html
Thanks!