Well, to recognize a card the SD card should just need to be inserted into the phone. Unless there is either something wrong with the card, it was formatted to another device (and encrypted by said device), the card is damaged, or the slot on the phone is damaged.
To move and/or download apps to a SD card requires that the phone be running, or upgradable to Android "Marshmallow" and not have had this option restricted by the manufacturer. Which does happen. Should you be running "Marshmallow", or able to upgrade to it, the following is how to make the change.
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 phone.
NOTE: If you don't reboot the phone, many things may not work correctly, so make sure you do.