OK to actually make the SD card able to run apps from you would need to make it "Internal" storage rather than "External". To do that you need to be running Android "Marshmallow" and the manufacturer has to have not restricted use of that option on that device. They do that sometimes, restrict it.
If both of those are met, then you can run any app you want from the card, as long as there is space. The catch is, you can run into errors/issues, if you are moving apps over to the card rather than downloading and installing them directly to it. Sometimes systems can register the space being taken up by them twice. Below are the instructions on how to turn a SD card into "Internal" storage, should you have the right version of Android and wish to try.
How to turn external SD card into internal storage on "Marshmallow".
NOTE: Please be sure you start with a blank SD card. It needs to be blank because when the card is converted to "Internal" storage, it will be formatted (wiped) and encoded (making the cards data only readable by that device).
1. Go to device “Settings”, then select “Storage”.
2. Select your "SD Card", then tap the “three-dot menu“ (top-right), now select “Settings” from in there.
3. Now select “Format as internal”, and then “Erase & Format”.
4. Your SD Card will now be formatted as internal storage.
5. Reboot your tablet.
NOTE: If you don't reboot the tablet, many things may not work correctly, so make sure you do.
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