Framework files, or framework APK files, are files that contain resources that are used by other APK files in the rom. The main one is "framework-res.apk" but some developers like to add their own to the mix as well. Framework files have, or should have otherwise it gets confusing, "res" in their filename.
Framework files need to be installed (via TMA, not your phone) before you decompile your APK. This will ensure that the resources in them will become available. This might be what's happening with your file. A few posts ago I shared a framework-res.apk from an Android 10 AOSP rom. Try installing that then decompiling and recompiling your file. If you still don't have any luck, could you share the file here please? I can give it a try and see what I can come up with.
Dragging and dropping here refers to a process done after recompiling. Essentially you'd open both the original and recompiled APK in 7zip or similar. Then you'd drag the changed files (like the "\res" folder, for instance) from the new APK into the old one. This ensures that the other files aren't touched.
Mainly this ensures that the META-INF folder isn't changed. This holds the key that the file is signed with and has to stay exactly the same (even down to the compression rate) or the new APK won't be installed. Apktool removes the need for this with the option I mentioned above but it seems that dragging and dropping might still be needed for Samsung.
Not the first time that Samsung has caused trouble, to be honest. Long-term subscribers of this thread may remember a few instances in the past where that company has given me a headache or two. Great hardware but not very friendly modder-friendly!
I've attached an apk of Speedtest that installs fine before decompiling/recompiling. Try this one and see how it goes! Thanks Ticklefish!