Well it is not going to work unless you are running Android version "Marshmallow". Prior versions of Android do not allow for making the SD card "Internal" storage rather than the standard "External" storage. Also, depending on the phones manufacturer, they may have limited that ability even if the phone is running "Marshmallow". Some have.
If you are running "Marshmallow" and wish to try and turn the card "Internal", please be sure you start with a blank SD card before trying the instructions below. Why? Well, because when the device formats and encodes the card to work as "Internal" storage, it will wipe any data that was previously on the card. Also, the SD cards data, once changed over and you start adding data, will no longer be accessible by any device other than the one this is being done in.
How to turn external SD card into internal storage on "Marshmallow".
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.
Now, if you aren't running "Marshmallow" and can't install it, and your phone isn't under warranty, you might consider rooting the device to work around things. For information on that please visit the "Rooting, Jailbreaking & Unlocking" Forum.
http/www.tomsguide.com/forum/forum-117.html