HOWEVER, if I upload this same APK to my actual Android Device, IT WORKS! Not only does it install, but it opens and runs my app just fine with no errors
This tells me it might be because your app uses native libraries which don’t match the emulator cpu architecture (see this question)
To get a more detailed error message, install your app via terminal:
adb install path_to_your_app/name_of_your_app.apk
You might see this:
adb: failed to install name_of_your_app.apk: Failure [INSTALL_FAILED_NO_MATCHING_ABIS: Failed to extract native libraries