I have this 64 gig microSD and it seems I can't utilize it
You can't move apps to memory card. It is possible only if sd card is adopted or via apps like link2sd (require root). Yes there is option move to sd card in app manager but that moves small amount of data to sd. So if you want more space for apps adopt your SD card and that's it. Some bare minimum is class 10 SD card or UHS I if you phone support it.